Search results for "char"
showing 10 items of 11394 documents
Microbiology and atmospheric processes: biological, physical and chemical characterization of aerosol particles
2008
Abstract. The interest in bioaerosols has traditionally been linked to health hazards for humans, animals and plants. However, several components of bioaerosols exhibit physical properties of great significance for cloud processes, such as ice nucleation and cloud condensation. To gain a better understanding of their influence on climate, it is therefore important to determine the composition, concentration, seasonal fluctuation, regional diversity and evolution of bioaerosols. In this paper, we will review briefly the existing techniques for detection, quantification, physical and chemical analysis of biological particles, attempting to bridge physical, chemical and biological methods for …
Humusica 2, article 19: Techno humus systems and global change - Conservation agriculture and 4/1000 proposal
2018
International audience; Philosophy can overlap pedology. It is not casual that life begins and finishes in the soil. We separated the concepts of Humipedon, Copedon and Lithopedon. Some sections were dedicated to the founders of the movement for a new type of agriculture (agroecology). They simply proclaim to accompany the process of natural evolution instead of spending a lot of energy in hunting competitor organisms with pesticides or boosting the soil with mineral fertilisation and tillage. The core of the article is built on a biological concept of the soil and shows researches supporting this view. After pointing to the soil structure and illustrating its natural genesis, explaining wh…
Evaluation of deep learning algorithms for national scale landslide susceptibility mapping of Iran
2021
The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses. In this study, we applied two novel deep learning algorithms, the recurrent neural network (RNN) and convolutional neural network (CNN), for national-scale landslide susceptibility mapping of Iran. We prepared a dataset comprising 4069 historical landslide locations and 11 conditioning factors (altitude, slope degree, profile curvature, distance to river, aspect, plan curvature, distance to road, distance to fault, rainfall, geology and land-sue) to construct a geospatial database and divided the data into the training and the testing dataset. We then d…
Controlled treatment of a high velocity anisotropic aquifer model contaminated by hexachlorocyclohexanes
2020
International audience; Xanthan gels were assessed to control the reductive dechlorination of hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs) in a strong permeability contrast and high velocity sedimentary aquifer. An alkaline degradation was selected because of the low cost of NaOH and Ca(OH)2. The rheology of alkaline xanthan gels and their ability to deliver alkalinity homogeneously, while maintaining the latter, were studied. Whereas the xanthan gels behaved like non-Newtonian shear-thinning fluids, alkalinity and Ca(OH)2 microparticles had detrimental effects, yet, the latter decreased with the shear-rate. Breakthrough curves for the NaOH and Ca(OH)2 in xanthan solutions, ca…
An improved understanding of the Alaska Coastal Current: the application of a bivalve growth-temperature model to reconstruct freshwater-influenced p…
2011
Shells of intertidal bivalve mollusks contain sub-seasonally to interannually resolved records of temperature and salinity variations in coastal settings. Such data are essential to understand changing land-sea interactions through time, specifically atmospheric (precipitation rate, glacial meltwater, river discharge) and oceanographic circulation patterns; however, independent temperature and salinity proxies are currently not available. We established a model for reconstructing daily water temperatures with an average standard error of ∼1.3 °C based on variations in the width of lunar daily growth increments of Saxidomus gigantea from southwestern Alaska, United States. Temperature explai…
Late glacial-postglacial North African landscape and forestmanagement : Palynological and anthracological studies in the caves of Kaf Taht el-Ghar an…
2021
This work presents the anthracological and archeopalynological results obtained within the project AGRIWESTMED (ERC AdG 230561), which has involved a comprehensive retrieval of archeobiological remains based on a systematic sampling strategy, beyond the recovery of the usual archeological materials. These surveys were conducted on three sites located in the North of Morocco: the cave of Kaf Taht-el-Ghar, 8 km southeast from Tetuan, and two caves within the El Khil complex, close to Tanger. Both plant micro- and macro-remains (charred wood) were studied through palynological and anthracological analyses, respectively.
The sedimentary and remote-sensing reflection of biomass burning in Europe
2018
Aim: We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10-500 µm) and macroscopic charcoal (MAC from sieves, particles > 100 µm). Location: North-south and east-west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period: Lake sediments and MODIS active fire and burned area…
Firewood and hearths: Middle Palaeolithic woody taxa distribution from El Salt, stratigraphic unit Xb (Eastern Iberia)
2017
Abstract Spatial analyses of Palaeolithic sites typically defined by hearth-related assemblages have been mostly based on lithic and faunal remains. By using spatial analysis methods in conjunction with analytical units with higher temporal resolution than typical stratigraphic units, synchronic and diachronic relationships between artifacts deposited during successive occupation events have been elucidated. Spatial analyses applied to archaeobotanical remains are scarce, and when available, are typically focused on carpological remains (seeds and fruits). The lack of spatial indicators among anthracological remains hampers obtaining significant data linked to the relationships established …
Land use change, soil erosion and alluvial dynamic in the lower Doubs Valley over the 1st millenium AD (Neublans, Jura, France)
2003
International audience; Geochemical and particle size analyses, surface scanning magnetic susceptibility, microscopic charcoal counting and pollen analysis, have been carried out on two cores from the lower Doubs valley in order to reconstruct the land use history. The interpretation of anthropogenic pollen indicators and micro-charcoal deposits is discussed in relation to the lithological variation of sedimentary accumulation and evolution of the settlement. The environmental changes which occurred during the 1st and the 6th century AD reflect the impact of human activities on the landscape in the immediate surroundings of the site. Multiproxy indicators indicate that soil erosion as a con…
Holocene vegetation and fire history of the mountains of Northern Sicily (Italy)
2016
Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests (Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species (Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso- mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees (Fagus sylvatica, Ilex aquifolium) dominat…