Search results for "Sediment"
showing 10 items of 1648 documents
Free-living amoebae in sediments from the Lascaux Cave in France
2013
The Lascaux Cave in France is an old karstic channel where the running waters are collected in a pool and pumped to the exterior. It is well-known that water bodies in the vicinity of humans are suspected to be reservoirs of amoebae and associated bacteria. In fact, the free-living amoebae Acanthamoeba astronyxis, Acanthamoeba castellanii, Acanthamoeba sp. and Hartmannella vermiformis were identified in the sediments of the cave using phylogenetic analyses and morphological traits. Lascaux Cave sediments and rock walls are wet due to a relative humidity near saturation and water condensation, and this environment and the presence of abundant bacterial communities constitute an ideal habitat…
Relationships between societies and their environment in the Sahel in southwestern Niger over the past four thousand years : a geoarchaeological appr…
2013
The Sahel, a zone between the Sahara Desert and the Sudan forests, is currently experiencing major environmental changes. Since the droughts in 1970s and 1980s, and with the high population growth rate, vegetation cover has deteriorated considerably, contributing to increased runoff and soil erosion. Starting from this observation, we undertook the study of past societies in the Niamey region, to assess their impact on the environment. The lack of archaeological data meant that it was necessary to identify key indicators of occupation during the Neolithic and the Iron Age. In addition to providing new evidence to date the Neolithic site of Kirkissoy, a sedimentary study was conducted on a p…
Observations préliminaires à l'étude des remplissages des tombes du Néolithique moyen I de Gurgy "Les Noisats" (Yonne)
2008
This paper presents results of experimental digging and filling of a pit in gravel context. That experimentation is the first step of an integrated analysis about sedimentary dynamic in neolithic burials from Gurgy « Les Noisats » (Yonne, France).
Erosion des sols viticoles par les évènements orageux (Vosne-Romanée) : quels risques pour le futur ?
2007
International audience; Des différences de maturité des raisins ont été constatées, en particulier entre les fruits produits sur les sols clairs et ceux provenant de vignes poussant sur des sols plus sombres. Ce constat a été testé par une expérience de mesures de températures en continu dans le Clos Vougeot et dans Les Cras, deux stations situées à la même altitude, distantes d'environ cent mètres et caractérisées par des sols plus bruns et plus argileux pour la première et par des sols plus clairs et pierreux pour la seconde. Dans les deux stations, les mesures de températures automatiques et régulières (toutes les trente minutes) ont été réalisées pendant un an à partir du 18 mai 2003, à…
A high-quality annually laminated sequence from Lake Belau, Northern Germany: Revised chronology and ist implications for palynological and tephrochr…
2012
International audience; The annually laminated record of Lake Belau offers an exceptional opportunity to investigate with high temporal resolution Holocene environmental change, aspects of climate history and human impact on the landscape. A new chronology based on varve counts, 14C-datings and heavy metal history has been established, covering the last 9400 years. Based on multiple varve counting on two core sequences, the easily countable laminated section spans about 7850 varve years (modelled age range c. 9430 to 1630 cal. BP). Not all of the record is of the same quality but approximately 69% of the varves sequence is classified to be of high quality and only c. 5% of low quality. The …
Distribution and sources of bulk organic matter (OM) on a tropical intertidal mud bank in French Guiana from elemental and isotopic proxies
2014
International audience; The mobile French Guiana coast is a shoreface region downdrift of the Amazon River, where enormous quantities of inorganic and organic materials are exchanged with the Atlantic Ocean. The rapid accumulation of these materials forms highly unstable shore-attached mud banks, which can be temporally emerged and then rapidly colonized and stabilized by microphytobenthos and opportunistic mangroves (i.e. Avicennia germinans). Mud banks are preferential sites for the accumulation and significant remineralization of organic matter (OM) due to intense erosion/deposition cycles and potential biological colonization. The distribution and sources of bulk sedimentary OM were cha…
Elevage et consommation en territoire arverne. : De l'agglomération d'Aulnat aux oppida du bassin clermontois, changements ou continuité ?
2010
Textes en français et en allemand. - Actes du 34ème colloque de l'AFEAF organisé du 13 au 16 mai 2010 à Aschaffenburg Allemagne). - Textes et avant-propos en allemand et en français. Bibliogr. en fin de contributions; International audience
Anthropogenic impact and environmental evolution of the last 55 years of the Gulf of Palermo (Sicily, Italy)
2009
Nonuniform sediment transport estimation in non-equlibrium situations: study cases
2014
Experimental Observation Of Turbulent Structures In A Straight Flume
2010
Experimental and theoretical studies of the structure of turbulence in open-channel flows have shown that the dynamics of the wall layer turbulence is dominated by the formation and growth of turbulent structures which evolve periodically as part of the so-called bursting phenomena. In the present paper experimental results obtained in a straight flume for different roughness conditions of the channel walls are described. The occurrence of turbulent events is verified by applying the conditioned quadrant analysis. The information about the spatial and temporal scales of the events is obtained through the space-time correlations of the conditioned data.