Search results for "LCA"
showing 10 items of 1995 documents
Degassing of gaseous (elemental and reactive) and particulate mercury from Mount Etna volcano (Southern Italy)
2007
Abstract There is an urgent need to better constrain the global rates of mercury degassing from natural sources, including active volcanoes. Hitherto, estimates of volcanic fluxes have been limited by the poorly determined speciation of Hg in volcanic emissions. Here, we present a systematic characterisation of mercury partitioning between gaseous (Hg(g)) and particulate (Hg(p)) forms in the volcanic plume of Mount Etna, the largest open-vent passively degassing volcano on Earth. We demonstrate that mercury transport is predominantly in the gas phase, with a mean Hg(p)/Hg(g) ratio of ∼0.01 by mass. We also present the first simultaneous measurement of divalent gaseous mercury ( Hg ( g ) II …
Mercury and halogen emissions from Masaya and Telica volcanoes, Nicaragua
2008
We report measurements of Hg, SO2, and halogens (HCl, HBr, HI) in volcanic gases from Masaya volcano, Nicaragua, and gaseous SO2 and halogens from Telica volcano, Nicaragua. Mercury measurements were made with a Lumex 915+ portable mercury vapor analyzer and gold traps, while halogens, CO2 and S species were monitored with a portable multi gas sensor and filter packs. Lumex Hg concentrations in the plume were consistently above background and ranged up to 350 ng m-3. Hg/SO2 mass ratios measured with the real-time instruments ranged from 1.1 × 10-7 to 3.5 × 10-5 (mean 2 × 10-5). Total gaseous mercury (TGM) concentrations measured by gold trap ranged from 100 to 225 ng m-3. Reactive gaseous m…
Facilitated transport of diuron and glyphosate in high copper vineyard soils.
2007
6 pages; International audience; The fate of organic herbicides applied to agricultural fields may be affected by other soil amendments, such as copper applied as a fungicide. The effect of copper on the leaching of diuron and glyphosate through a granitic and a calcareous soil was studied in the laboratory using sieved-soil columns. Each soil was enriched with copper sulfate to obtain soil copper concentrations of 125, 250, 500, and 1000 mg kg(-1). Glyphosate leaching was influenced by soil pH and copper concentration, whereas diuron leaching was not. In the calcareous soil, glyphosate leaching decreased as copper levels increased from 17 mg kg(-1) (background) to 500 mg kg(-1). In the gra…
Dažādo metālisko elementu noteikšana ķērpjos (Parmelia sulcata) Kupravas apkārtnē
2022
Dažādu metālisko elementu noteikšana ķērpjos (Parmelia sulcata) Kupravas apkārtnē. Freimanis R., zinātniskā darba vadītājs Ķīm. mag. Lazarenko V. Bakalaura darbs, 31 lpp., 7 attēli, 9 tabulas, 28 literatūras avoti, 3 pielikumi. Latviešu valodā. Bakalaura darba izstrādes ietvaros, tika analizēts dažādo metālisko elementu saturs lapu ķērpju sugā (Parmelia sulcata) Kupravas apkārtnē. Tika izvēlētas trīs dažādas Kupravas apkārtnes teritorijas – bijušās Kupravas drenu cauruļu rūpnīcas teritorija, Kupravas dzīvojamais rajons, bijušajā militārās armijas daļa un Strautu mežs, kas atrodas ~6 km attālumā no Kupravas, kā tīrāka teritorija. Metālisko elementu saturs ķērpjos (Parmelia sulcata) tika note…
Enhanced volcanic hot-spot detection using MODIS IR data: results from the MIROVA system
2015
We describe a new volcanic hotspot detection system, named Middle InfraRed Observation of Volcanic Activity (MIROVA), based on the analysis of infrared data acquired by the Moderate Resolution Imaging Spectroradiometer sensor (MODIS). MIROVA uses the middle infrared radiation (MIR), measured by MODIS, in order to detect and measure the heat radiation deriving from volcanic activity. The algorithm combines spectral and spatial principles, allowing the detection of heat sources from 1 megawatt (MW) to more than 10 gigawatt (GW). This provides a unique opportunity to: (i) recognize small-scale variations in thermal output that may precede the onset of effusive activity; (ii) track the advance …
Hydrogen emissions from Erebus volcano, Antarctica
2012
International audience; The continuous measurement of molecular hydrogen (H2) emissions from passively degassing volcanoes has recently been made possible using a new generation of low-cost electrochemical sensors. We have used such sensors to measure H2, along with SO2, H2O and CO2, in the gas and aerosol plume emitted from the phonolite lava lake at Erebus volcano, Antarctica. The measurements were made at the crater rim between December 2010 and January 2011. Combined with measurements of the long-term SO2 emission rate for Erebus, they indicate a characteristic H2 flux of 0.03 kg s-1 (2.8 Mg day-1). The observed H2 content in the plume is consistent with previous estimates of redox cond…
Magnesium silicate hydrate (M-S-H) characterization : temperature, calcium, aluminium and alkali
2017
The various options to store radioactive wastes in deep geological strata considered in France or Switzerland include the use of large volumes of cementitious materials for infrastructure in contact with argillaceous rocks. So-called low-pH binders were developed to minimize disruption to the surrounding rock by the alkaline plume. Studies conducted on the interaction zone between concrete and clay systematically highlighted the formation of magnesium silicate phases including magnesium silicate hydrate (M-S-H) at the interfaces, which can presently be modeled only partially due to incomplete thermodynamic data. The purpose of this study was to characterize these phases in temperature, alum…
Paramagnetic Cobalt and Nickel Derivatives of Alcaligenes denitrificans Azurin and Its M121Q Mutant. A 1H NMR Study
1996
Using cobalt or nickel to replace copper in native azurin allows one to fingerprint the metal coordination site of the protein. The metal sites of wild type Alcaligenes denitrificans azurin and its M121Q mutant are clearly distinguishable through the paramagnetic 1H NMR spectra of the Ni(II) and Co(II) derivatives. In the wild type azurin, Gly45 coordinates to nickel or cobalt, while Met121 appears as a weak metal ligand. On the contrary, in the M121Q azurin mutant, the metal exhibits a clear preference for the Gln121, which coordinates through the side chain carbonyl oxygen, and Gly45 is not a ligand. Changes in the isotropic shifts and relaxation properties of signals from the Cys112, His…
Gender as a key factor in trace metal and metalloid content of human scalp hair. A multi-site study
2016
This multi-site study discusses the content of metals and metalloids (MM) in scalp hair of children, living in different environmental contexts, with the purpose of verifying if hair level of some MM is distinctively gender-specific. A total of 943 hair samples (537 females and 406 males) from adolescents were analysed for their content of Al, As, Ba, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, U, V and Zn. Elemental quantification was performed by ICP-MS. The obtained data identified different metal distributions in adolescent girls which exhibited significantly higher hair concentrations of some trace metals, especially Sr, Zn and Ni, than boys. On the base of the median value, hai…
Non-uniform displacement and strain between the soleus and gastrocnemius subtendons of rat Achilles tendon
2018
Achilles tendon (AT) comprises of 3 subtendons arising from the soleus (SOL) and the lateral (LG) and medial (MG) heads of the gastrocnemius muscle. While recent human studies show differential displacement within AT, these displacements have not been attributed to specific subtendons. We tested the hypothesis that the SOL and LG subtendons show differential displacement and strain during various combinations of SOL, LG, and MG excitations. Movement of knots, sutured onto SOL and LG subtendons of 12 Wistar rats, was videotaped, while the muscles were stimulated intramuscularly and ankle torque was assessed. When SOL only was stimulated, the plantar flexion torque was the smallest among the …