Search results for "iron"
showing 10 items of 31116 documents
Modelling the removal and reversible immobilization of murine noroviruses in a Phaeozem under various contamination and rinsing conditions
2018
International audience; Enteric viruses entering the soil with contaminated irrigation water can reach groundwater or be internalized in plants through their roots without being inactivated. Their fate in the soil depends on the virus, the soil and the soil solution. In order to write a mathematical model suitable for a Calcaric Phaeozem, we investigated the removal of murine norovirus and reversible immobilization in aggregate columns according to a saturation procedure, conditions between contamination and rinsing time, temperature and soil solution. Viruses were quantified before and after 0.45‐μm filtration with an RT‐qPCR (real‐time polymerase chain reaction). Experimental results supp…
Toimijuus korkeakoulutettujen suomen oppijoiden visuaalisissa narratiiveissa
2018
This socioculturally informed study explores how highly educated Finnish language learners represent their agency in visual narratives. Learners (n=59) were asked to draw two pictures of themselves as Finnish language users and provide verbal interpretations of the drawings. The aim of using visual narratives is to reach aspects such as feelings and beliefs which might be difficult to express verbally. The data were analyzed first by using visual grammar set out by Kress and van Leeuwen (2006) and secondly by content analysis. The findings suggest that learners saw Finnish language as a tool for oral communication. However, difficulties with speaking and listening appeared to restrict learn…
Regional Farmers’ Perception and Societal Issues in Vineyards Affected by High Erosion Rates
2021
We explore the current situation in a viticultural region in Eastern Spain from a holistic and multifaceted research approach, which allowed us to understand the biophysical conditions, economic cost, social impact, and perception of the farmers’ community to the use of catch crops. A survey of the perception of the farmers, and an assessment of the biophysical impact of catch crops (CC) and tillage (C = Control plot) on soil organic matter, bulk density, infiltration capacity (single ring infiltrometer), and runoff generation and soil erosion (rainfall simulation experiments) was carried out. Two representative fields as study sites were selected in Les Alcusses valley, within Els Alforins…
Chemistry and fluxes of major and trace element from worldwide passive degassing volcanoes: a critical review
2015
Volcanic emissions represent one of the most important natural sources of trace elements (e.g. As, Cd, Cu, Hg, Pb, Sb, Tl and Zn) into the atmosphere, sequentially influencing the hydrosphere, lithosphere and biosphere. The human health hazard during episodic volcanic eruptions generally follows from deposition of coarse and fine particles (2.5-10 and < 2.5 μm) that produces effects such as asthma and lung and respiratory disease. Regarding passive degassing volcanoes, the harmful effects of fluorine fumigation are known both for vegetation (foliar necrosis) and human/animals (fluorosis), but only a few studies have been focused on the effects of potentially toxic trace elements. From a …
A Low-Cost Smartphone Sensor-Based UV Camera for Volcanic SO2 Emission Measurements
2017
Recently, we reported on the development of low-cost ultraviolet (UV) cameras, based on the modification of sensors designed for the smartphone market. These units are built around modified Raspberry Pi cameras (PiCams; ≈USD 25), and usable system sensitivity was demonstrated in the UVA and UVB spectral regions, of relevance to a number of application areas. Here, we report on the first deployment of PiCam devices in one such field: UV remote sensing of sulphur dioxide emissions from volcanoes; such data provide important insights into magmatic processes and are applied in hazard assessments. In particular, we report on field trials on Mt. Etna, where the utility of these devices in quantif…
A model of degassing for Stromboli volcano
2010
International audience; A better understanding of degassing processes at open-vent basaltic volcanoes requires collection of new datasets of H2O–CO2–SO2 volcanic gas plume compositions, which acquisition has long been hampered by technical limitations. Here, we use the MultiGAS technique to provide the best-documented record of gas plume discharges from Stromboli volcano to date. We show that Stromboli's gases are dominated by H2O (48–98 mol%; mean, 80%), and by CO2 (2–50 mol%; mean, 17%) and SO2 (0.2–14 mol%; mean, 3%). The significant temporal variability in our dataset reflects the dynamic nature of degassing process during Strombolian activity; which we explore by interpreting our gas m…
Sulfur Degassing From Steam-Heated Crater Lakes: El Chichón (Chiapas, Mexico) and Víti (Iceland)
2018
The composition of the gases released by El Chichón (Chiapas, Mexico) and Víti (Askja volcano, Iceland) volcanic lakes is examined by Multi-GAS for the first time. Our results demonstrate that H2S and SO2 are degassed by these pH 2–3 lakes. We find higher CO2/H2S and H2/H2S ratios in the lakes' emissions (31–5,685 and 0.6–35, respectively) than in the fumarolic gases feeding the lakes (13–33 and 0.08–0.5, respectively), evidencing that only a fraction (0.2–5.4% at El Chichón) of the H2S(g) contributed by the subaquatic fumaroles ultimately reaches the atmosphere. At El Chichón, we estimate a H2S output from the crater lake of 0.02–0.06 t/day. Curiously, SO2 is also detected at trace levels …
Volcanic Plume CO2 Flux Measurements at Mount Etna by Mobile Differential Absorption Lidar
2017
Volcanic eruptions are often preceded by precursory increases in the volcanic carbon dioxide (CO2) flux. Unfortunately, the traditional techniques used to measure volcanic CO2 require near-vent, in situ plume measurements that are potentially hazardous for operators and expose instruments to extreme conditions. To overcome these limitations, the project BRIDGE (BRIDging the gap between Gas Emissions and geophysical observations at active volcanoes) received funding from the European Research Council, with the objective to develop a new generation of volcanic gas sensing instruments, including a novel DIAL-Lidar (Differential Absorption Light Detection and Ranging) for remote (e.g., distal) …
Ultraviolet imaging of volcanic plumes: A new paradigm in volcanology
2017
Ultraviolet imaging has been applied in volcanology over the last ten years or so. This provides considerably higher temporal and spatial resolution volcanic gas emission rate data than available previously, enabling the volcanology community to investigate a range of far faster plume degassing processes than achievable hitherto. To date, this has covered rapid oscillations in passive degassing through conduits and lava lakes, as well as puffing and explosions, facilitating exciting connections to be made for the first time between previously rather separate sub-disciplines of volcanology. Firstly, there has been corroboration between geophysical and degassing datasets at â1 Hz, expeditin…
Evolution of Seismicity During a Stalled Episode of Reawakening at Cayambe Volcano, Ecuador
2021
Cayambe Volcano is an ice-capped, 5,790 m high, andesitic-dacitic volcanic complex, located on the equator in the Eastern Cordillera of the Ecuadorian Andes. An eruption at Cayambe would pose considerable hazards to surrounding communities and a nationally significant agricultural industry. Although the only historically documented eruption was in 1785, it remains persistently restless and long-period (LP) seismicity has been consistently observed at the volcano for over 10 years. However, the sparse monitoring network, and complex interactions between the magmatic, hydrothermal, glacial, and tectonic systems, make unrest at Cayambe challenging to interpret. In June 2016 a seismic “crisis” …