Nitrogen Oxides in the North Atlantic Troposphere: Impacts of Boreal Wildfire and Anthropogenic Emissions

Nitrogen oxides play a crucial role in the budget of tropospheric ozone (O sub(3)) and the formation of the hydroxyl radical. Anthropogenic activities and boreal wildfires are large sources of emissions in the atmosphere. However, the influence of the transport of these emissions on nitrogen oxides and O sub(3) levels at hemispheric scales is not well understood, in particular due to a lack of nitrogen oxides measurements in remote regions. In order to address these deficiencies, measurements of NO, NO sub(2) and NO sub(y) (total reactive nitrogen oxides) were made in the lower free troposphere (FT) over the central North Atlantic region (Pico Mountain station, 38 degree N 28 degree W, 2.3 km asl) from July 2002 to August 2005. These measurements reveal a well-defined seasonal cycle of nitrogen oxides (NO sub(x) = NO+NO sub(2) and NO sub(y)) in the background central North Atlantic lower FT, with higher mixing ratios during the summertime. Observed NO sub(x) and NO sub(y) levels are consistent with long-range transport of emissions, but with significant removal en-route to the measurement site. Reactive nitrogen largely exists in the form of PAN and HNO sub(3) ( similar to 80-90% of NO sub(y)) all year round. A shift in the composition of NO sub(y) from dominance of PAN to dominance of HNO sub(3) occurs from winter-spring to summer-fall, as a result of changes in temperature and photochemistry over the region. Analysis of the long-range transport of boreal wildfire emissions on nitrogen oxides provides evidence of the very large-scale impacts of boreal wildfires on the tropospheric NO sub(x) and O sub(3) budgets. Boreal wildfire emissions are responsible for significant shifts in the nitrogen oxides distributions toward higher levels during the summer, with medians of NO sub(y) (117-175 pptv) and NO sub(x) (9-30 pptv) greater in the presence of boreal wildfire emissions. Extreme levels of NO sub(x) (up to 150 pptv) and NO sub(y) (up to 1100 pptv) observed in boreal wildfire plumes suggest that decomposition of PAN to NO sub(x) is a significant source of NO sub(x), and imply that O sub(3) formation occurs during transport. Ozone levels are also significantly enhanced in boreal wildfire plumes. However, a complex behavior of O sub(3) is observed in the plumes, which varies from significant to lower O sub(3) production to O sub(3) destruction. Long-range transport of anthropogenic emissions from North America also has a significant influence on the regional NO sub(x) and O sub(3) budgets. Transport of pollution from North America causes significant enhancements on nitrogen oxides year-round. Enhancements of CO, NO sub(y) and NO sub(x) indicate that, consistent with previous studies, more than 95% of the NO sub(x) emitted over the U.S. is removed before and during export out of the U.S. boundary layer. However, about 30% of the NO sub(x) emissions exported out of the U.S. boundary layer remain in the airmasses. Since the lifetime of NO sub(x) is shorter than the transport timescale, PAN decomposition and potentially photolysis of HNO sub(3) provide a supply of NO sub(x) over the central North Atlantic lower FT. Observed Delta O sub(3)/ Delta NO sub(y) and large NO sub(y) levels remaining in the North American plumes suggest potential O sub(3) formation well downwind from North America. Finally, a comparison of the nitrogen oxides measurements with results from the global chemical transport (GCT) model GEOS-Chem identifies differences between the observations and the model. GEOS-Chem reproduces the seasonal variation of nitrogen oxides over the central North Atlantic lower FT, but does not capture the magnitude of the cycles. Improvements in our understanding of nitrogen oxides chemistry in the remote FT and emission sources are necessary for the current GCT models to adequately estimate the impacts of emissions on tropospheric NO sub(x) and the resulting impacts on the O sub(3) budget.

Electro-Deposition of Iron from a Chloride Bath

Iron was electro-deposited from a ferrous chloride bath. Studies were made of deposits formed when current density was varied, and fin­ally when both current density and temperature were changed. An attempt was made to lay the ground work for a long range study of the chloride bath, and to determine the most simple conditions possible for obtaining a smooth, even, and thick deposit.

Risk of severe asthma episodes predicted from fluctuation analysis of airway function

Asthma is an increasing health problem worldwide, but the long-term temporal pattern of clinical symptoms is not understood and predicting asthma episodes is not generally possible. We analyse the time series of peak expiratory flows, a standard measurement of airway function that has been assessed twice daily in a large asthmatic population during a long-term crossover clinical trial. Here we introduce an approach to predict the risk of worsening airflow obstruction by calculating the conditional probability that, given the current airway condition, a severe obstruction will occur within 30 days. We find that, compared with a placebo, a regular long-acting bronchodilator (salmeterol) that is widely used to improve asthma control decreases the risk of airway obstruction. Unexpectedly, however, a regular short-acting beta2-agonist bronchodilator (albuterol) increases this risk. Furthermore, we find that the time series of peak expiratory flows show long-range correlations that change significantly with disease severity, approaching a random process with increased variability in the most severe cases. Using a nonlinear stochastic model, we show that both the increased variability and the loss of correlations augment the risk of unstable airway function. The characterization of fluctuations in airway function provides a quantitative basis for objective risk prediction of asthma episodes and for evaluating the effectiveness of therapy.

Genome sequence, comparative analysis, and population genetics of the domestic horse

We report a high-quality draft sequence of the genome of the horse (Equus caballus). The genome is relatively repetitive but has little segmental duplication. Chromosomes appear to have undergone few historical rearrangements: 53% of equine chromosomes show conserved synteny to a single human chromosome. Equine chromosome 11 is shown to have an evolutionary new centromere devoid of centromeric satellite DNA, suggesting that centromeric function may arise before satellite repeat accumulation. Linkage disequilibrium, showing the influences of early domestication of large herds of female horses, is intermediate in length between dog and human, and there is long-range haplotype sharing among breeds.

High Resolution Image Correspondences for Video Post-Production

We present an algorithm for estimating dense image correspondences. Our versatile approach lends itself to various tasks typical for video post-processing, including image morphing, optical flow estimation, stereo rectification, disparity/depth reconstruction, and baseline adjustment. We incorporate recent advances in feature matching, energy minimization, stereo vision, and data clustering into our approach. At the core of our correspondence estimation we use Efficient Belief Propagation for energy minimization. While state-of-the-art algorithms only work on thumbnail-sized images, our novel feature downsampling scheme in combination with a simple, yet efficient data term compression, can cope with high-resolution data. The incorporation of SIFT (Scale-Invariant Feature Transform) features into data term computation further resolves matching ambiguities, making long-range correspondence estimation possible. We detect occluded areas by evaluating the correspondence symmetry, we further apply Geodesic matting to automatically determine plausible values in these regions.

Recent environmental change and trace metal pollution in World Heritage Bathurst Harbour, southwest Tasmania, Australia

Bathurst Harbour in World Heritage southwest Tasmania, Australia, is one of the world’s most pristine estuarine systems. At present there is a lack of data on pollution impacts or long-term natural variability in the harbor. A ca. 350-year-old 210Pb-dated sediment core was analysed for trace metals to track pollution impacts from local and long-range sources. Lead and antimony increased from AD 1870 onwards, which likely reflects remote (i.e. mainland Australian and global) atmospheric pollution sources. Variability in the concentrations of copper and zinc closely followed the history of mining activities in western Tasmania, which began in the AD 1880s. Tin was generally low throughout the core, except for a large peak in AD 1989 ± 0.5 years, which may be a consequence of input from a local small-scale alluvial tin mine. Changes in diatom assemblages were also investigated. The diatom flora was composed mostly of planktonic freshwater and benthic brackish-marine species, consistent with stratified estuarine conditions. Since mining began, however, an overall decrease in the proportion of planktonic to benthic taxa occurred, with the exception of two distinct peaks in the twentieth century that coincided with periods of high rainfall. Despite the region’s remoteness, trace metal analyses revealed evidence of atmospheric pollution from Tasmanian and possibly longer-range mining activities. This, together with recent low rainfall, appears to have contributed to altering the diatom assemblages in one of the most pristine temperate estuaries in the world.

Landscape connectivity, habitat structure and activity of bat guilds in farmland-dominated matrices

Agricultural intensification has caused a decline in structural elements in European farmland, where natural habitats are increasingly fragmented. The loss of habitat structures has a detrimental effect on biodiversity and affects bat species that depend on vegetation structures for foraging and commuting. We investigated the impact of connectivity and configuration of structural landscape elements on flight activity, species richness and diversity of insectivorous bats and distinguished three bat guilds according to species-specific bioacoustic characteristics. We tested whether bats with shorter-range echolocation were more sensitive to habitat fragmentation than bats with longer-range echolocation. We expected to find different connectivity thresholds for the three guilds and hypothesized that bats prefer linear over patchy landscape elements. Bat activity was quantified using repeated acoustic monitoring in 225 locations at 15 study plots distributed across the Swiss Central Plateau, where connectivity and the shape of landscape elements were determined by spatial analysis (GIS). Spectrograms of bat calls were assigned to species with the software batit by means of image recognition and statistical classification algorithms. Bat activity was significantly higher around landscape elements compared to open control areas. Short- and long-range echolocating bats were more active in well-connected landscapes, but optimal connectivity levels differed between the guilds. Species richness increased significantly with connectivity, while species diversity did not (Shannon's diversity index). Total bat activity was unaffected by the shape of landscape elements. Synthesis and applications. This study highlights the importance of connectivity in farmland landscapes for bats, with shorter-range echolocating bats being particularly sensitive to habitat fragmentation. More structurally diverse landscape elements are likely to reduce population declines of bats and could improve conditions for other declining species, including birds. Activity was highest around optimal values of connectivity, which must be evaluated for the different guilds and spatially targeted for a region's habitat configuration. In a multi-species approach, we recommend the reintroduction of structural elements to increase habitat heterogeneity should become part of agri-environment schemes.

Novel pseudo-staphylococcal cassette chromosome mec element (ψSCCmec57395) in methicillin-resistant Staphylococcus pseudintermedius CC45

Genetic characterization of methicillin-resistant Staphylococcus pseudintermedius (MRSP) from Thailand and Israel revealed the presence of a predominant atypical clonal lineage which was not typeable by SmaI-PFGE and SCCmec typing. All the atypical isolates (n = 34) belonged to CC45 (30 ST45 and 2 ST179 isolates, 1 ST57 isolate, and 1 ST85 isolate). The isolates originated from healthy and diseased dogs and cats, as well as from the environment of one clinic. Cfr9I-pulsed-field gel electrophoresis (Cfr9I-PFGE) and dru typing permitted the further distinction of CC45 isolates from the two different countries. Microarray analysis identified genes that confer resistance to β-lactams (mecA; blaZ), aminoglycosides [aac(6')-Ie-aph(2')-Ia; aph(3')-III; ant(6)-Ia], macrolides and lincosamides [erm(B)], tetracyclines [tet(M)], trimethoprim [dfr(G)], streptothricin (sat4), and chloramphenicol (catpC221). Fluoroquinolone resistance was attributed to specific amino acid substitutions, i.e., Ser84Leu in GyrA and Ser80Ile and Asp84Asn in GrlA. A novel pseudo-staphylococcal cassette chromosome (ΨSCCmec57395) element was identified in MRSP strain 57395 (sequence type ST45) by whole-genome sequencing. The 12,282-bp ΨSCCmec57395 element contained a class C1 mec gene complex but no ccr genes. In addition to the methicillin resistance gene mecA, ΨSCCmec57395 also carried determinants of resistance to heavy metals, such as arsenic, cadmium, and copper. Bsu36I restriction analysis of the ΨSCCmec57395 element amplified by long-range PCR revealed the presence of ΨSCCmec57395 in the 33 additional isolates of MRSP CC45. The ΨSCCmec57395 element represents a new class of SCCmec and has been identified in MRSP of CC45, which is a predominant clonal lineage in Israel and Thailand.

Calculation of crystal optical properties from molecular electron density

We have recently developed a method to obtain distributed atomic polarizabilities adopting a partitioning of the molecular electron density (for example, the Quantum Theory of Atoms in Molecules, [1]), calculated with or without an applied electric field. The procedure [2] allows to obtained atomic polarizability tensors, which are perfectly exportable, because quite representative of an atom in a given functional group. Among the many applications of this idea, the calculation of crystal susceptibility is easily available, either from a rough estimation (the polarizability of the isolated molecule is used) or from a more precise estimation (the polarizability of a molecule embedded in a cluster representing the first coordination sphere is used). Lorentz factor is applied to include the long range effect of packing, which is enhancing the molecular polarizability. Simple properties like linear refractive index or the gyration tensor can be calculated at relatively low costs and with good precision. This approach is particularly useful within the field of crystal engineering of organic/organometallic materials, because it would allow a relatively easy prediction of a property as a function of the packing, thus allowing "reverse crystal engineering". Examples of some amino acid crystals and salts of amino acids [3] will be illustrated, together with other crystallographic or non-crystallographic applications. For example, the induction and dispersion energies of intermolecular interactions could be calculated with superior precision (allowing anisotropic van der Waals interactions). This could allow revision of some commonly misunderstood intermolecular interactions, like the halogen bonding (see for example the recent remarks by Stone or Gilli [4]). Moreover, the chemical reactivity of coordination complexes could be reinvestigated, by coupling the conventional analysis of the electrostatic potential (useful only in the circumstances of hard nucleophilic/electrophilic interaction) with the distributed atomic polarizability. The enhanced reactivity of coordinated organic ligands would be better appreciated. [1] R. F. W. Bader, Atoms in Molecules: A Quantum Theory. Oxford Univ. Press, 1990. [2] A. Krawczuk-Pantula, D. Pérez, K. Stadnicka, P. Macchi, Trans. Amer. Cryst. Ass. 2011, 1-25 [3] A. S. Chimpri1, M. Gryl, L. H.R. Dos Santos1, A. Krawczuk, P. Macchi Crystal Growth & Design, in the press. [4] a) A. J. Stone, J. Am. Chem. Soc. 2013, 135, 7005−7009; b) V. Bertolasi, P. Gilli, G. Gilli Crystal Growth & Design, 2013, 12, 4758-4770.

Hochwasser-«Katastrophen» in Basel vom 13. bis 21. Jahrhundert Rekonstruktion, Deutung und Lerneffekte

Magnitudes of peak discharges of 43 non-instrumentally measured Rhine river floods at Basel were reconstructed. The methodology is based on a range of different historic sources, containing flood information (including traditional urban inundation reference points from flood reports of medieval and early modern period chroniclers as well as 19th century journalists, flood marks, paintings and drawings, town maps, longitudinal and cross profiles etc.). These traditional pre-instrumental “flood information systems” still existed in the 19th century, when in 1808 the first instrumental hydrological measurements started. They thus could be calibrated with instrumental measurements in the 19th century overlapping period. The result is a 743 year long quantified Rhine river flood series. Floods of both periods (pre-instrumental as well as instrumental) can thus be directly compared for the very first time. The long-range consequences of rivers Kander and Aare deviations in 1714 and 1878 are reflected in a distinct change of magnitudes of peak discharges in Basel. A clear flood “disaster gap” appears in the 20th century. The lack of any extreme floods for such a long time is completely unique during the 743-year period of analysis. This result will influence the statistical assessment of once-in-a-century events, which might be of great interest for insurance campanies.

Chiral Templating Activity of Tris(bipyridine)ruthenium(II) Cation in the Design of Three-Dimensional (3D) Optically Active Oxalate-Bridged {[Ru(bpy) 3 ][Cu 2 x Ni 2(1 - x ) (C 2 O 4 ) 3 ]} n (0 ≤ x ≤ 1; bpy = 2,2‘-bipyridine): Structural, Optical, and Magnetic Studies

Three-dimensional oxalate-based {[Ru(bpy)3][Cu2xNi2(1-x)(ox)3]}n (0≤ x ≤ 1, ox = C2O42-, bpy = 2,2‘bipyridine) were synthesized. The structure was determined for x = 1 by X-ray diffraction on single crystal. The compound crystallizes in the cubic space group P4132. It shows a three-dimensional 10-gon 3-connected (10,3) anionic network where copper(II) has an unusual tris(bischelated) environment. X-ray powder diffraction patterns and their Rietveld refinement show that all the compounds along the series are isostructural and single-phased. According to X-ray absorption spectroscopy, copper(II) and nickel(II) have an octahedral environment, respectively elongated and trigonally distorted. As shown by natural circular dichroism, the optically active forms of {[Ru(bpy)3][CuxNi2(1-x)(ox)3]}n are obtained starting from resolved Δ- or Λ-[Ru(bpy)3]2+. The Curie−Weiss temperatures range between −55 (x = 1) and −150 K (x = 0). The antiferromagnetic exchange interaction thus decreases when the copper contents increases in agreement with the crystallographic structure of the compounds and the electronic structure of the metal ions. At low temperature, the compounds exhibit complex long-range ordered magnetic behavior.

The Exploitation of Versatile Building Blocks for the Self-Assembly of Novel Molecular Magnets

Using molecular building blocks to self-assemble lattices supporting long-range magnetic order is currently an active area of solid-state chemistry. Consequently, it is the realm of supramolecular chemistry that synthetic chemists are turning to in order to develop techniques for the synthesis of structurally well-defined supramolecular materials. In recent years we have investigated the versatility and usefulness of two classes of molecular building blocks, namely, tris-oxalato transition-metal (M. Pilkington and S. Decurtins, in “Magnetoscience—From Molecules to Materials,” Wiley–VCH, 2000), and octacyanometalate complexes (Pilkington and Decurtins, Chimia 54, 593 (2001)), for applications in the field of molecule-based magnets. Anionic, tris-chelated oxalato building blocks are able to build up two-dimensional honeycomb-layered structural motifs as well as three-dimensional decagon frameworks. The discrimination between the crystallization of the two- or three-dimensional structures relies on the choice of the templating counterions (Decurtins, Chimia 52, 539 (1998); Decurtins et al. Mol. Cryst. Liq. Cryst. 273, 167 (1995); New J. Chem. 117 (1998)). These structural types display a range of ferro, ferri, and antiferromagnetic properties (Pilkington and Decurtins, in “Magnetoscience—From Molecules to Materials”). Octacyanometalate building blocks self-assemble to afford two new classes of cyano-bridged compounds namely, molecular clusters and extended three dimensional networks (J. Larionova et al., Angew. Chem. Int. Ed. 39, 1605 (2000); Pilkington et al., in preparation). The molecular cluster with a MnII9MoV6 core has the highest ground state spin value, S=51/2, reported to-date (Larionova et al., Angew. Chem. Int. Ed. 39, 1605 (2000)). In the high-temperature regime, the magnetic properties are characterized by ferromagnetic intracluster coupling. In the magnetic range below 44 K, the magnetic cluster signature is lost as possibly a bulk behavior starts to emerge. The three-dimensional networks exhibit both paramagnetic and ferromagnetic behavior, since the magnetic properties of these materials directly reflect the electronic configuration of the metal ion incorporated into the octacyanometalate building blocks (Pilkington et al., in preparation). For both the oxalate- and cyanide-bridged materials, we are able to manipulate the magnetic properties of the supramolecular assemblies by tuning the electronic configurations of the metal ions incorporated into the appropriate molecular building blocks (Pilkington and Decurtins, in “Magnetoscience—From Molecules to Materials,” Chimia 54, 593 (2000)).

Molecular-Based Magnetism in High-Spin Molecular Clusters and Three-Dimensional Networks Based on Cyanometalate Building Blocks

The field of molecule-based magnets is a relatively new branch of chemistry, which involves the design and study of molecular compounds that exhibit a spontaneous magnetic ordering below a critical temperature, Tc. One major goal involves the design of materials with tuneable Tc's for specific applications in memory storage devices. Molecule-based magnets with high magnetic ordering temperatures have recently been obtained from bimetallic and mixed-valence transition metal μ-cyanide complexes of the Prussian blue family. Since the μ-cyanide linkages permit an interaction between paramagnetic metal ions, cyanometalate building blocks have found useful applications in the field of molecule-based magnets. Our work involves the use of octacyanometalate building blocks for the self-assembly of two new classes of magnetic materials namely, high-spin molecular clusters which exhibit both ferromagnetic intra- and intercluster coupling, and specific extended network topologies which show long-range ferromagnetic ordering.

Morphological alterations in the liver of yellow perch (Perca flavescens) from a biological mercury hotspot

Mercury (Hg) contamination is a global issue due to its anthropogenic release, long-range transport, and deposition in remote areas. In Kejimkujik National Park and National Historic Site, Nova Scotia, Canada, high concentrations of total mercury (THg) were found in tissues of yellow perch (Perca flavescens). The aim of this study was to evaluate a possible relationship between THg concentrations and the morphology of perch liver as a main site of metal storage and toxicity. Yellow perch were sampled from five lakes known to contain fish representing a wide range in Hg concentrations in fall 2013. The ultrastructure of hepatocytes and the distribution of Hg within the liver parenchyma were analyzed by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). The relative area of macrophage aggregates (MAs) in the liver was determined using image analysis software and fluorescence microscopy. No relation between general health indicators (Fulton's condition index) and THg was observed. In line with this, TEM examination of the liver ultrastructure revealed no prominent pathologies related to THg accumulation. However, a morphological parameter that appeared to increase with muscle THg was the relative area of MAs in the liver. The hepatic lysosomes appeared to be enlarged in samples with the highest THg concentrations. Interestingly, EELS analysis revealed that the MAs and hepatic lysosomes contained Hg.

In-situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris Megacity

A detailed characterization of air quality in the megacity of Paris (France) during two 1-month intensive campaigns and from additional 1-year observations revealed that about 70% of the urban background fine particulate matter (PM) is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in situ measurements during short intensive and longer-term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE chemistry transport models. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by comprehensive analysis of aerosol mass spectrometer (AMS), radiocarbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions constituted less than 20%in winter and 40%in summer of carbonaceous fine PM, unexpectedly small for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin, i.e., from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant, flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only being partially responsible for its own average and peak PM levels has important implications for air pollution regulation policies.