Laboratory and field measurements of enantiomeric and non-enantiomeric biogenic VOCs and anthropogenic BTEX compounds

This doctoral thesis was focused on the investigation of enantiomeric and non-enantiomeric biogenic organic compound (BVOC) emissions from both leaf and canopy scales in different environments. In addition, the anthropogenic compounds benzene, toluene, ethylbenzene, and xylenes (BTEX) were studied. BVOCs are emitted into the lower troposphere in large quantities (ca. 1150 Tg C ·yr-1), approximately an order of magnitude greater than the anthropogenic VOCs. BVOCs are particularly important in tropospheric chemistry because of their impact on ozone production and secondary organic aerosol formation or growth. The BVOCs examined in this study were: isoprene, (-)/ (+)-α-pinene, (-)/ (+)-ß-pinene, Δ-3-carene, (-)/ (+)-limonene, myrcene, eucalyptol and camphor, as these were the most abundant BVOCs observed both in the leaf cuvette study and the ambient measurements. In the laboratory cuvette studies, the sensitivity of enantiomeric enrichment change from the leaf emission has been examined as a function of light (0-1600 PAR) and temperature (20-45°C). Three typical Mediterranean plant species (Quercus ilex L., Rosmarinus officinalis L., Pinus halepensis Mill.) with more than three individuals of each have been investigated using a dynamic enclosure cuvette. The terpenoid compound emission rates were found to be directly linked to either light and temperature (e.g. Quercus ilex L.) or mainly to temperature (e.g. Rosmarinus officinalis L., Pinus halepensis Mill.). However, the enantiomeric signature showed no clear trend in response to either the light or temperature; moreover a large variation of enantiomeric enrichment was found during the experiment. This enantiomeric signature was also used to distinguish chemotypes beyond the normal achiral chemical composition method. The results of nineteen Quercus ilex L. individuals, screened under standard conditions (30°C and 1000 PAR) showed four different chemotypes, whereas the traditional classification showed only two. An enclosure branch cuvette set-up was applied in the natural boreal forest environment from four chemotypes of Scots pine (Pinus sylvestris) and one chemotype of Norway spruce (Picea abies) and the direct emissions compared with ambient air measurements above the canopy during the HUMPPA-COPEC 2010 summer campaign. The chirality of a-pinene was dominated by (+)-enantiomers from Scots pine while for Norway spruce the chirality was found to be opposite (i.e. Abstract II (-)-enantiomer enriched) becoming increasingly enriched in the (-)-enantiomer with light. Field measurements over a Spanish stone pine forest were performed to examine the extent of seasonal changes in enantiomeric enrichment (DOMINO 2008). These showed clear differences in chirality of monoterpene emissions. In wintertime the monoterpene (-)-a-pinene was found to be in slight enantiomeric excess over (+)-a-pinene at night but by day the measured ratio was closer to one i.e. racemic. Samples taken the following summer in the same location showed much higher monoterpene mixing ratios and revealed a strong enantiomeric excess of (-)-a-pinene. This indicated a strong seasonal variance in the enantiomeric emission ratio which was not manifested in the day/night temperature cycles in wintertime. A clear diurnal cycle of enantiomeric enrichment in a-pinene was also found over a French oak forest and the boreal forest. However, while in the boreal forest (-)-a-pinene enrichment increased around the time of maximum light and temperature, the French forest showed the opposite tendency with (+)-a-pinene being favored. For the two field campaigns (DOMINO 2008 and HUMPPA-COPEC 2010), the BTEX were also investigated. For the DOMINO campaign, mixing ratios of the xylene isomers (meta- and para-) and ethylbenzene, which are all well resolved on the ß-cyclodextrin column, were exploited to estimate average OH radical exposures to VOCs from the Huelva industrial area. These were compared to empirical estimates of OH based on JNO2 measured at the site. The deficiencies of each estimation method are discussed. For HUMPPA-COPEC campaign, benzene and toluene mixing ratios can clearly define the air mass influenced by the biomass burning pollution plume from Russia.

Search for a spin-dependent short-range force between nucleons with a 3 He, 129 Xe clock-comparison experiment

Light pseudoscalar bosons, such as the axion that was originally proposed as a solution of the strong CP problem, would cause a new spin-dependent short-range interaction. In this thesis, an experiment is presented to search for axion mediated short-range interaction between a nucleon and the spin of a polarized bound neutron. This interaction cause a shift in the precession frequency of nuclear spin-polarized gases in the presence of an unpolarized mass. To get rid of magnetic field drifts co-located, nuclear spin polarized 3He and 129Xe atoms were used. The free nuclear spin precession frequencies were measured in a homogeneous magnetic guiding field of about 350nT using LTc SQUID detectors. The whole setup was housed in a magnetically shielded room at the Physikalisch Technische Bundesanstalt (PTB) in Berlin. With this setup long nuclear spin-coherence times, respectively, transverse relaxation times of 5h for 129Xe and 53h for 3He could be achieved. The results of the last run in September 2010 are presented which give new upper limits on the scalar-pseudoscalar coupling of axion-like particles in the axion-mass window from 10^(-2) eV to 10^(-6) eV. The laboratory upper bounds were improved by up to 4 orders of magnitude.

Experiment in Quantization: Atomic Line Spectra

Laboratory exercises that confront students with decisive ouantum ohenomena nrovide valuable motivation for the kudy of quantum m&hanics. The idea that microscopic matter exists in quantized states can be demonstrated with modern versions of historic experiments: atomic line snectra. blackbodv radiation. and resonance potentials. In this experiment, we present a strikingly simple and visual method for determining the wavelength of spectral lines. This experiment not only shows the inadequacy of classical physics, but also indicates the power of optical measurements.

Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C. dissolved inorganic C and SO(4) concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of clay surfaces.

Effect of Population Heterogenization on the Reproducibility of Mouse Behavior: A Multi-Laboratory Study

In animal experiments, animals, husbandry and test procedures are traditionally standardized to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioral tests, accounting for poor reproducibility, and that this can be avoided by population heterogenization through systematic variation of experimental conditions. Here, we examined whether a simple form of heterogenization effectively improves reproducibility of test results in a multi-laboratory situation. Each of six laboratories independently ordered 64 female mice of two inbred strains (C57BL/6NCrl, DBA/2NCrl) and examined them for strain differences in five commonly used behavioral tests under two different experimental designs. In the standardized design, experimental conditions were standardized as much as possible in each laboratory, while they were systematically varied with respect to the animals' test age and cage enrichment in the heterogenized design. Although heterogenization tended to improve reproducibility by increasing within-experiment variation relative to between-experiment variation, the effect was too weak to account for the large variation between laboratories. However, our findings confirm the potential of systematic heterogenization for improving reproducibility of animal experiments and highlight the need for effective and practicable heterogenization strategies.

[High altitude pulmonary edema. An experiment of nature to study the underlying mechanisms of hypoxic pulmonary hypertension and pulmonary edema in humans]

High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, it has become clear that the results of high-altitude research may have important implications not only for the understanding of diseases in the millions of people living permanently at high altitude, but also for the treatment of hypoxemia-related disease states in patients living at low altitude. High-altitude pulmonary edema (HAPE) is a life-threatening condition occurring in predisposed, but otherwise healthy subjects, and, therefore, allows to study underlying mechanisms of pulmonary edema in humans, in the absence of confounding factors. Over the past decade, evidence has accumulated that HAPE results from the conjunction of two major defects, augmented alveolar fluid flooding resulting from exaggerated hypoxic pulmonary hypertension, and impaired alveolar fluid clearance related to defective respiratory transepithelial sodium transport. Here, after a brief presentation of the clinical features of HAPE, we review this novel concept. We provide experimental evidence for the novel concept that impaired pulmonary endothelial and epithelial nitric oxide synthesis and/or bioavailability may represent the central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and alveolar fluid flooding. We demonstrate that exaggerated pulmonary hypertension, while possibly a condition sine qua non, may not be sufficient to cause HAPE, and how defective alveolar fluid clearance may represent a second important pathogenic mechanism. Finally, we outline how this insight gained from studies in HAPE may be translated into the management of hypoxemia related disease states in general.

Designing forest biodiversity experiments: general considerations illustrated by a new large experiment in subtropical China

1. Biodiversity-ecosystem functioning (BEF) experiments address ecosystem-level consequences of species loss by comparing communities of high species richness with communities from which species have been gradually eliminated. BEF experiments originally started with microcosms in the laboratory and with grassland ecosystems. A new frontier in experimental BEF research is manipulating tree diversity in forest ecosystems, compelling researchers to think big and comprehensively. 2. We present and discuss some of the major issues to be considered in the design of BEF experiments with trees and illustrate these with a new forest biodiversity experiment established in subtropical China (Xingangshan, Jiangxi Province) in 2009/2010. Using a pool of 40 tree species, extinction scenarios were simulated with tree richness levels of 1, 2, 4, 8 and 16 species on a total of 566 plots of 25.8x25.8m each. 3. The goal of this experiment is to estimate effects of tree and shrub species richness on carbon storage and soil erosion; therefore, the experiment was established on sloped terrain. The following important design choices were made: (i) establishing many small rather than fewer larger plots, (ii) using high planting density and random mixing of species rather than lower planting density and patchwise mixing of species, (iii) establishing a map of the initial ecoscape' to characterize site heterogeneity before the onset of biodiversity effects and (iv) manipulating tree species richness not only in random but also in trait-oriented extinction scenarios. 4. Data management and analysis are particularly challenging in BEF experiments with their hierarchical designs nesting individuals within-species populations within plots within-species compositions. Statistical analysis best proceeds by partitioning these random terms into fixed-term contrasts, for example, species composition into contrasts for species richness and the presence of particular functional groups, which can then be tested against the remaining random variation among compositions. 5. We conclude that forest BEF experiments provide exciting and timely research options. They especially require careful thinking to allow multiple disciplines to measure and analyse data jointly and effectively. Achieving specific research goals and synergy with previous experiments involves trade-offs between different designs and requires manifold design decisions.

Standard methods for maintaining adult Apis mellifera in cages under in vitro laboratory conditions

Adult honey bees are maintained in vitro in laboratory cages for a variety of purposes. For example, researchers may wish to perform experiments on honey bees caged individually or in groups to study aspects of parasitology, toxicology, or physiology under highly controlled conditions, or they may cage whole frames to obtain newly emerged workers of known age cohorts. Regardless of purpose, researchers must manage a number of variables, ranging from selection of study subjects (e.g. honey bee subspecies) to experimental environment (e.g. temperature and relative humidity). Although decisions made by researchers may not necessarily jeopardize the scientific rigour of an experiment, they may profoundly affect results, and may make comparisons with similar, but independent, studies difficult. Focusing primarily on workers, we provide recommendations for maintaining adults under in vitro laboratory conditions, whilst acknowledging gaps in our understanding that require further attention. We specifically describe how to properly obtain honey bees, and how to choose appropriate cages, incubator conditions, and food to obtain biologically relevant and comparable experimental results. Additionally, we provide broad recommendations for experimental design and statistical analyses of data that arises from experiments using caged honey bees. The ultimate goal of this, and of all COLOSS BEEBOOK papers, is not to stifle science with restrictions, but rather to provide researchers with the appropriate tools to generate comparable data that will build upon our current understanding of honey bees.

Characterization of granite matrix porosity and pore-space geometry by in situ and laboratory methods

Most available studies of interconnected matrix porosity of crystalline rocks are based on laboratory investigations; that is, work on samples that have undergone stress relaxation and were affected by drilling and sample preparation. The extrapolation of the results to in situ conditions is therefore associated with considerable uncertainty, and this was the motivation to conduct the ‘in situ Connected Porosity’ experiment at the Grimsel Test Site (Central Swiss Alps). An acrylic resin doped with fluorescent agents was used to impregnate the microporous granitic matrix in situ around an injection borehole, and samples were obtained by overcoring. The 3-D structure of the porespace, represented by microcracks, was studied by U-stage fluorescence microscopy. Petrophysical methods, including the determination of porosity, permeability and P -wave velocity, were also applied. Investigations were conducted both on samples that were impregnated in situ and on non-impregnated samples, so that natural features could be distinguished from artefacts. The investigated deformed granites display complex microcrack populations representing a polyphase deformation at varying conditions. The crack population is dominated by open cleavage cracks in mica and grain boundary cracks. The porosity of non-impregnated samples lies slightly above 1 per cent, which is 2–2.5 times higher than the in situ porosity obtained for impregnated samples. Measurements of seismic velocities (Vp ) on spherical rock samples as a function of confining pressure, spatial direction and water saturation for both non-impregnated and impregnated samples provide further constraints on the distinction between natural and induced crack types. The main conclusions are that (1) an interconnected network of microcracks exists in the whole granitic matrix, irrespective of the distance to ductile and brittle shear zones, and (2) conventional laboratory methods overestimate the matrix porosity. Calculations of contaminant transport through fractured media often rely on matrix diffusion as a retardation mechanism.

Anisotropic diffusion at the field scale in a 4-year multi-tracer diffusion and retention experiment – I: Insights from the experimental data

Abstract Claystones are considered worldwide as barrier materials for nuclear waste repositories. In the Mont Terri underground research laboratory (URL), a nearly 4-year diffusion and retention (DR) experiment has been performed in Opalinus Clay. It aimed at (1) obtaining data at larger space and time scales than in laboratory experiments and (2) under relevant in situ conditions with respect to pore water chemistry and mechanical stress, (3) quantifying the anisotropy of in situ diffusion, and (4) exploring possible effects of a borehole-disturbed zone. The experiment included two tracer injection intervals in a borehole perpendicular to bedding, through which traced artificial pore water (APW) was circulated, and a pressure monitoring interval. The APW was spiked with neutral tracers (HTO, HDO, H2O-18), anions (Br, I, SeO4), and cations (Na-22, Ba-133, Sr-85, Cs-137, Co-60, Eu-152, stable Cs, and stable Eu). Most tracers were added at the beginning, some were added at a later stage. The hydraulic pressure in the injection intervals was adjusted according to the measured value in the pressure monitoring interval to ensure transport by diffusion only. Concentration time-series in the APW within the borehole intervals were obtained, as well as 2D concentration distributions in the rock at the end of the experiment after overcoring and subsampling which resulted in �250 samples and �1300 analyses. As expected, HTO diffused the furthest into the rock, followed by the anions (Br, I, SeO4) and by the cationic sorbing tracers (Na-22, Ba-133, Cs, Cs-137, Co-60, Eu-152). The diffusion of SeO4 was slower than that of Br or I, approximately proportional to the ratio of their diffusion coefficients in water. Ba-133 diffused only into �0.1 m during the �4 a. Stable Cs, added at a higher concentration than Cs-137, diffused further into the rock than Cs-137, consistent with a non-linear sorption behavior. The rock properties (e.g., water contents) were rather homogeneous at the centimeter scale, with no evidence of a borehole-disturbed zone. In situ anisotropy ratios for diffusion, derived for the first time directly from field data, are larger for HTO and Na-22 (�5) than for anions (�3�4 for Br and I). The lower ionic strength of the pore water at this location (�0.22 M) as compared to locations of earlier experiments in the Mont Terri URL (�0.39 M) had no notable effect on the anion accessible pore fraction for Cl, Br, and I: the value of 0.55 is within the range of earlier data. Detailed transport simulations involving different codes will be presented in a companion paper.

In-situ diffusion of HTO, 22Na+, Cs+ and I- in Opalinus Clay at the Mont Terri underground rock laboratory

The diffusion properties of the Opalinus Clay were studied in the underground research laboratory at Mont Terri (Canton Jura, Switzerland) and the results were compared with diffusion data measured in the laboratory on small-scale samples. The diffusion of HTO, Na-22(+), Cs+ and I- were investigated for a period of 10 months. The diffusion equipment used in the field experiment was designed in such a way that a solution of tracers was circulated through a sintered metal screen placed at the end of a borehole drilled in the formation. The concentration decrease caused by the diffusion of tracers into the rock could be followed with time and allowed first estimations of the effective diffusion coefficient. After 10 months, the diffusion zone was over-cored and the tracer profiles measured. From these profiles, effective diffusion coefficients and rock capacity factors Could be extracted by applying a two-dimensional transport model including diffusion and sorption. The simulations were done with the reactive transport code CRUNCH. In addition, results obtained from through-diffusion experiments oil small-sized samples with HTO, Cl-36(-) and Na-22(+) are presented and compared with the in situ data. In all cases. excellent agreement between the two data sets exists. Results for Cs+ indicated five times higher diffusion rates relative to HTO. Corresponding laboratory diffusion measurements are still lacking. However. our Cs+ data are in qualitative agreement wish through-diffusion data for Callovo-Oxfordian argillite rock samples. which also indicate significantly higher effective diffusivities for Cs+ relative to HTO.

Diffusion of HTO, Br-, I-, Cs+, Sr-85(2+) and Co-60(2+) in a clay formation: Results and modelling from an in situ experiment in Opalinus Clay

The migration of radioactive and chemical contaminants in clay materials and argillaceous host rocks is characterised by diffusion and retention processes. Valuable information on such processes can be gained by combining diffusion studies at laboratory scale with field migration tests. In this work, the outcome of a multi-tracer in situ migration test performed in the Opalinus Clay formation in the Mont Terri underground rock laboratory (Switzerland) is presented. Thus, 1.16 x 10(5) Bq/L of HTO, 3.96 x 10(3) Bq/L of Sr-85, 6.29 x 10(2) Bq/L of Co-60, 2.01 x 10(-3) mol/L Cs, 9.10 x 10(-4) mol/L I and 1.04 x 10(-3) mol/L Br were injected into the borehole. The decrease of the radioisotope concentrations in the borehole was monitored using in situ gamma-spectrometry. The other tracers were analyzed with state-of-the-art laboratory procedures after sampling of small water aliquots from the reservoir. The diffusion experiment was carried out over a period of one year after which the interval section was overcored and analyzed. Based on the experimental data from the tracer evolution in the borehole and the tracer profiles in the rock, the diffusion of tracers was modelled with the numerical code CRUNCH. The results obtained for HTO (H-3), I- and Br- confirm previous lab and in situ diffusion data. Anionic fluxes into the formation were smaller compared to HTO because of anion exclusion effects. The migration of the cations Sr-85(2+), Cs+ and Co-60(2+) was found to be governed by both diffusion and sorption processes. For Sr-85(2+), the slightly higher diffusivity relative to HTO and the low sorption value are consistent with laboratory diffusion measurements on small-scale samples. In the case of Cs+, the numerically deduced high diffusivity and the Freundlich-type sorption behaviour is also supported by ongoing laboratory data. For Co, no laboratory diffusion data were yet available for comparison; however, the modelled data suggests that Co-60(2+) sorption was weaker than would be expected from available batch sorption data. Overall, the results demonstrate the feasibility of the experimental setup for obtaining high-quality diffusion data for conservative and sorbing tracers. (C) 2007 Elsevier Ltd. All rights reserved.

Addendum: search for ν μ → ν e oscillations with the OPERA experiment in the CNGS beam

A first result of the search for ν ( )μ( ) → ν ( )e( ) oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ν ( )e( ) in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters θ (new) and suggested by the LSND and MiniBooNE experiments. For large values (>0.1 eV(2)), the OPERA 90% C.L. upper limit on sin(2)(2θ (new)) based on a Bayesian statistical method reaches the value 7.2 × 10(−3).

New results on ν μ → ν τ appearance with the OPERA experiment in the CNGS beam

The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the νμ→ντ channel, via the detection of the τ-leptons created in charged current ντ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first ντ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional ντ candidate has been observed. The significance of the two events in terms of a νμ→ντ oscillation signal is of 2.40 σ.

Search for νμ→νe oscillations with the OPERA experiment in the CNGS beam

A first result of the search for nu(mu)->nu(e) oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of nu(e) in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters theta(new) and Delta m(new)(2) suggested by the LSND and MiniBooNE experiments. For large Delta m(new)(2) values (>0.1 eV(2)), the OPERA 90% C.L. upper limit on sin(2)(2 theta(new)) based on a Bayesian statistical method reaches the value 7.2 x 10(-3).