Search results for "element"
showing 10 items of 13601 documents
Speleothem records decadal to multidecadal hydroclimate variations in southwestern Morocco during the last millennium
2017
Abstract This study presents the first well-dated high resolution stable isotope ( δ 18 O and δ 13 C ) and trace element (Mg and Sr) speleothem records from southwestern Morocco covering the last 1000 yrs. Our records reveal substantial decadal to multidecadal swings between dry and humid periods, consistent with regional paleorecords with prevailing dry conditions during the Medieval Climate Anomaly (MCA), wetter conditions during the second part of the Little Ice Age (LIA), and a trend towards dry conditions during the current warm period. These coherent regional climate signals suggest common climate controls. Statistical analyses indicate that the climate of southwestern Morocco remaine…
Relief and calcium from gypsum as key factors for net inorganic carbon accumulation in soils of a semiarid Mediterranean environment
2021
Abstract In semiarid environments, the total inorganic carbon (TIC) in soil may contribute to the total carbon (C) pool more than the total organic C pool (TOC), thus playing a key role in storing atmospheric CO2. However, due to the different origin pathways of soil carbonates, not all of the TIC pool can be accounted for CO2 sequestration. Indeed, the inorganic C can be accounted for a net sink of CO2 only when calcium (Ca2+) forming carbonates originate from non-carbonate minerals (atmogenic inorganic C, AIC). The aim of this study carried out in a gypsiferous area is to investigate the dissolution of Ca2+ that comes from gypsum (CaSO4·2H2O) in the formation of soil atmogenic carbonates …
Sensitivity and mode spectrum of a frequency-output silicon pressure sensor
1988
The vibrational mode spectrum of a silicon vibrating pressure sensor is investigated. Particular attention is given to the analysis of the vibration shapes, quality factors and relative sensitivity of the resonance frequencies as a function of pressure. It is shown that a pressure sensitivity of a few parts per million at one atmosphere can be achieved. Some comments are also made regarding an improved design of the device.
Ultra-sensitive chiral sensing and analysis from the nanoscale to the earth’s atmosphere
2020
Chirality plays an essential role in life and, therefore, in modem science. I’ll present novel technologies for ultra-sensitive, absolute, chiral sensing and analysis, in all phases, from the nanoscale to the earth’s atmosphere.
Vibronic structures in the visible luminescence of silica nanoparticles
2014
Time resolved photoluminescence investigation in air and in vacuum atmosphere of the visible luminescence related to silica surface defects is here reported. Two contributions can be singled out: one, observed both in air and in vacuum, is the well-known blue band, peaked around 2.8 eV decaying in ∼5 ns; the other, only observed in vacuum, is a structured emission in the violet range characterized by two vibronic progressions spaced 1370 cm−1 and 360 cm−1 decaying in ∼100 ns. In contrast with previous attribution, the well distinguishable spectroscopic properties together with the observation of the effects induced by the interaction with nitrogen allow to state that the emission bands orig…
Simulation of organics in the atmosphere: evaluation of EMACv2.54 with the Mainz Organic Mechanism (MOM) coupled to the ORACLE (v1.0) submodel
2021
Abstract. An updated and expanded representation of organics in the chemistry general circulation model EMAC (ECHAM5/MESSy for Atmospheric Chemistry) has been evaluated. First, the comprehensive Mainz Organic Mechanism (MOM) in the submodel MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere) was activated with explicit degradation of organic species up to five carbon atoms and a simplified mechanism for larger molecules. Second, the ORACLE submodel (version 1.0) considers now condensation on aerosols for all organics in the mechanism. Parameterizations for aerosol yields are used only for the lumped species that are not included in the explicit mechanism. The simultaneous…
Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F–BEACh 2014 field study
2017
Abstract. The chemical composition of organic aerosols was analyzed using complementary mass spectrometric techniques during a field study in Central Europe in July 2014 (Fichtelgebirge – Biogenic Emission and Aerosol Chemistry, F–BEACh 2014). Aerosols were analyzed in real-time by Aerosol Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (AeroFAPA–MS), Aerosol Mass Spectrometry (AMS), and Chemical Ionization Atmospheric-Pressure interface Time-of-Flight Mass Spectrometry (CI–APiToF–MS). In addition, offline detection of acidic organic compounds was conducted by non-target screening of filter samples using High Resolution Mass Spectrometry (HRMS) in combination with Ultra-High Pressu…
Climate Extreme Versus Carbon Extreme: Responses of Terrestrial Carbon Fluxes to Temperature and Precipitation
2020
International audience; Carbon fluxes at the land-atmosphere interface are strongly influenced by weather and climate conditions. Yet what is usually known as “climate extremes” does not always translate into very high or low carbon fluxes or so-called “carbon extremes.” To reveal the patterns of how climate extremes influence terrestrial carbon fluxes, we analyzed the interannual variations in ecosystem carbon fluxes simulated by the Terrestrial Biosphere Models (TBMs) in the Inter-Sectoral Impact Model Intercomparison Project. At the global level, TBMs simulated reduced ecosystem net primary productivity (NPP; 18.5 ± 9.3 g C m−2 yr−1), but enhanced heterotrophic respiration (Rh; 7 ± 4.6 g…
Study on ambient concentrations of PM10, PM10-2.5, PM2.5 and gaseous pollutants. Trace elements and chemical speciation of atmospheric particulates
2010
Abstract This study provides the first comprehensive report on mass concentrations of particulate matter of various sizes, inorganic and organic gas concentrations monitored at three sampling sites in the city of Palermo (Sicily, Italy). It also provides information on the water-soluble species and trace elements. A total of 2054 PM10 (1333) and PM2.5 (721) daily measurements were collected from November 2006 to February 2008. The highest mass concentrations were observed at the urban stations, average values being about two times higher than those at the suburban (control) site. Time variations in PM10 and also PM10–2.5 were observed at the urban stations, the highest concentrations being …
Mass levels, crustal component and trace elements in PM10 in Palermo, Italy.
2007
Abstract Results concerning the levels and elemental compositions of daily PM 10 samples collected at four air quality monitoring sites in Palermo (Italy) are presented. The highest mean value of PM 10 concentrations (46 μg m −3 , with a peak value of 158 μg m −3 ) was recorded at the Di Blasi urban station, and the lowest at Boccadifalco station (25 μg m −3 ), considered as a sub-urban background station. Seventeen elements (Al, As, Ba, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Sb, Sr, U, V, Zn) were measured by ICP-MS. Al and Fe showed the highest concentrations, indicating the significant contribution of soil and resuspended mineral particles to atmospheric PM 10 . Ba, Cr, Cu, Mn, Mo, Ni, Pb, …