Spatial and temporal variations in the distribution of birch trees and airborne Betula pollen in Ireland

In an Irish context, and indeed in Northern Europe, one of the most important allergenic pollen types is birch (Betula spp.). Thus, forecasts of such atmospheric pollen are important tools for helping patients suffering from allergenic rhinitis and/or atopic asthma to avoid high ambient concentrations and manage their symptoms. This work aims to improve knowledge about the spatial and temporal variations in the distribution of birch trees and airborne Betula pollen in Ireland, which is an important step towards producing such forecasts. The footprint of airborne Betula pollen recorded in Ireland was determined by using HYSPLIT backward Lagrangian dispersion modelling methodology and mapped using Geographic Information System (GIS) software during the Main Pollen Season (MPS) and for days with airborne concentrations > 80 pollen grains/m3 in Dublin and Carlow (72 km apart) for 2018 and 2019. An inventory of birch trees within broadleaved forests was constructed using statistical data from different vegetation inventories for Ireland with a resolution of 100 m x 100 m. Historical datasets of airborne Betula pollen recorded in Dublin during 1978-1980 and 2010-2011 were also related to changes in land cover and climatic conditions over the same period. Dispersion modelling showed that air masses arriving in Ireland on days with Betula pollen concentrations >80 pollen grains/m3 resided for a longer time over Great Britain. The birch tree inventory for Ireland will enhance the performance of forecast models. Airborne Betula pollen concentrations in Ireland have increased over the last 40 years, which is related to concomitant increases in the fraction of birch trees in forest areas as well as the ornamental use of birch trees in urban areas and their reaching maturity. Climate change did not seem to influence birch pollination

Seasonal variability and source apportionment of volatile organic compounds (VOCs) in the Paris megacity (France)

Within the framework of air quality studies at the megacity scale, highly time-resolved volatile organic compound (C₂–C₈) measurements were performed in downtown Paris (urban background sites) from January to November 2010. This unique dataset included non-methane hydrocarbons (NMHCs) and aromatic/oxygenated species (OVOCs) measured by a GC-FID (gas chromatograph with a flame ionization detector) and a PTR-MS (proton transfer reaction – mass spectrometer), respectively. This study presents the seasonal variability of atmospheric VOCs being monitored in the French megacity and their various associated emission sources. Clear seasonal and diurnal patterns differed from one VOC to another as the result of their different origins and the influence of environmental parameters (solar radiation, temperature). Source apportionment (SA) was comprehensively conducted using a multivariate mathematical receptor modeling. The United States Environmental Protection Agency's positive matrix factorization tool (US EPA, PMF) was used to apportion and quantify ambient VOC concentrations into six different sources. The modeled source profiles were identified from near-field observations (measurements from three distinct emission sources: inside a highway tunnel, at a fireplace and from a domestic gas flue, hence with a specific focus on road traffic, wood-burning activities and natural gas emissions) and hydrocarbon profiles reported in the literature. The reconstructed VOC sources were cross validated using independent tracers such as inorganic gases (NO, NO₂, CO), black carbon (BC) and meteorological data (temperature). The largest contributors to the predicted VOC concentrations were traffic-related activities (including motor vehicle exhaust, 15 % of the total mass on the annual average, and evaporative sources, 10 %), with the remaining emissions from natural gas and background (23 %), solvent use (20 %), wood-burning (18 %) and a biogenic source (15 %). An important finding of this work is the significant contribution from wood-burning, especially in winter, where it could represent up to  ∼  50 % of the total mass of VOCs. Biogenic emissions also surprisingly contributed up to  ∼  30 % in summer (due to the dominating weight of OVOCs in this source). Finally, the mixed natural gas and background source exhibited a high contribution in spring (35 %, when continental air influences were observed) and in autumn (23 %, for home heating consumption)

ACTRIS ACSM intercomparison - Part 1: Reproducibility of concentration and fragment results from 13 individual Quadrupole Aerosol Chemical Speciation Monitors (Q-ACSM) and consistency with co-located instruments

As part of the European ACTRIS project, the first large Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM) intercomparison study was conducted in the region of Paris for 3 weeks during the late-fall - early-winter period (November-December 2013). The first week was dedicated to the tuning and calibration of each instrument, whereas the second and third were dedicated to side-by-side comparison in ambient conditions with co-located instruments providing independent information on submicron aerosol optical, physical, and chemical properties. Near real-time measurements of the major chemical species (organic matter, sulfate, nitrate, ammonium, and chloride) in the non-refractory submicron aerosols (NR-PM) were obtained here from 13 Q-ACSM. The results show that these instruments can produce highly comparable and robust measurements of the NR-PM total mass and its major components. Taking the median of the 13 Q-ACSM as a reference for this study, strong correlations (r > 0.9) were observed systematically for each individual Q-ACSM across all chemical families except for chloride for which three Q-ACSMs showing weak correlations partly due to the very low concentrations during the study. Reproducibility expanded uncertainties of Q-ACSM concentration measurements were determined using appropriate methodologies defined by the International Standard Organization (ISO 17025, 1999) and were found to be 9, 15, 19, 28, and 36 % for NR-PM, nitrate, organic matter, sulfate, and ammonium, respectively. However, discrepancies were observed in the relative concentrations of the constituent mass fragments for each chemical component. In particular, significant differences were observed for the organic fragment at mass-to-charge ratio 44, which is a key parameter describing the oxidation state of organic aerosol. Following this first major intercomparison exercise of a large number of Q-ACSMs, detailed intercomparison results are presented, along with a discussion of some recommendations about best calibration practices, standardized data processing, and data treatment

Exceptional symmetry by genomic word: A Statistical Analysis

Single-strand DNA symmetry is pointed as a universal law observed in the genomes from all living organisms. It is a somewhat broadly defined concept, which has been refined into some more specific measurable effects. Here we discuss the exceptional symmetry effect. Exceptional symmetry is the symmetry effect beyond that expected in independence contexts, and it can be measured for each word, for each equivalent composition group, or globally, combining the effects of all possible words of a given length. Global exceptional symmetry was found in several species, but there are genomic words with no exceptional symmetry effect, whereas others show a very high exceptional symmetry effect. In this work, we discuss a measure to evaluate the exceptional symmetry effect by symmetric word pair, and compare it with others. We present a detailed study of the exceptional symmetry by symmetric pairs and take the CG content into account. We also introduce and discuss the exceptional symmetry profile for the DNA of each organism, and we perform a multiple comparison for 31 genomes: 7 viruses; 5 archaea; 5 bacteria; 14 eukaryotes

Depoliticization at the EU Level : Delegitimization and Circumvention of Representative Democracy in the Government of Europe

International audienceThis article defends the hypothesis that depoliticization practices in the European Union stem from the EU's institutions and actors's relationship, both singular and longstanding, with "the political" and representative democracy. We thus propose to take a perspective opposite to a dominant reading that regards depoliticization as a recent response to a critical juncture in EU integration, and in particular to the growing objections to which the EU is subjected. To do so, this article starts by highlighting the omnipresence of the logics of depoliticization and listing its main methodsexpertise, informal negotiation, permanent consultation of interest groupsin making European policies. Trying then to identify what feeds these depoliticization initiatives, it underlines a relationship of distrust regarding the mechanisms of representative democracy, which, far from being the exclusive prerogative of "euro-officials", is widely shared among Europe's professionals and closely linked to the genesis and institutionalization of the European field of power (Georgakakis, Rowel, 2013)