Inverse modeling of past lead atmospheric deposition in South Greenland

The aim of this study is to model atmospheric lead fluxes in two different paleoenvironmental records located in southern Greenland. Fifty five sediment samples collected from the Lake Igaliku sedimentary sequence were analyzed for lead and aluminum concentrations, and lead isotopic compositions. The second archive consists in a previously published dataset, obtained from a minerogenic peat deposit, located at Tasiusaq, 16 km northwest from Lake Igaliku. A flux model fitted to both dataset produces similar results, allowing past anthropogenic atmospheric deposition to be reconstructed. This original method can be easily adapted for other studies where natural inputs dominate over discrete a…

Les sites ecclésiaux et monastiques de l’archipel du Kvarner (Croatie) : campagne 2016

La campagne 2016 du programme de recherche sur les sites ecclesiaux et monastiques de l’archipel du Kvarner a essentiellement porte sur la fouille du petit complexe antique et medieval septentrional du site de Mirine-Fulfinum – secteur dit de « l’eglise a trois absides » – (ile de Krk), du 11 au 23 avril 2016, et sur la poursuite de la fouille de la grande eglise paleochretienne du complexe de Martinscica (ile de Cres) du 27 juin au 14 juillet (fig. 1). Fig. 1 – Carte de l’archipel du Kvarner...

Geochemical characterization of soil organic matter and variability of a postglacial detrital organic supply (chaillexon lake, france)

Fluctuations climatiques et réponses environnementales : l'exemple du bassin de Chaillexon (Doubs, France)

International audience

Sur la présence de matières organiques mésocénozoïques dans des humus actuels (bassin de Chaillexon, Doubs, France)

Abstract The optical analysis in the Chaillexon watershed (Doubs, France), of the present soils' humus layers' organic matter points out the contribution of Meso-Cenozoic organic matter in addition to the one produced by vegetal cover. Their relative occurrence varies in each layer: in the reverse of that of vegetal organic matter, the relative amount of Meso-Cenozoic organic matter increases according to the depth. That result shows that the total organic matter amounts in soils (and its evaluation) do not only depend on the net primary production and that geological formations have to be taken into account. Moreover, it suggests that present and past detrital supplies are concerned with ‘…

Testing a portable laser-induced breakdown spectroscopy system on geological samples.

9 pages; International audience; This paper illustrates the potentialities of a home-made portable LIBS (laser-induced breakdown spectroscopy) instrument in Earth sciences, more particularly in geochemically recognizing (i) tephra layers in lacustrine sediments and (ii) fossilization processes in ammonites. Abundances for selected lines of Al, Ca, Fe, Ti, Ba and Na were determined in lacustrine chalk sediments of the Jura, where the Laacher See Tephra (LST) layer is recorded. A statistical treatment of elemental maps produced from the section of a sedimentary column containing the LST event allows instrumental conditions to be optimized. Accumulating spectra from close shot positions gives …

Impact of Holocene climate variability on lacustrine records and human settlements in South Greenland

Due to its sensitivity to climate changes, south Greenland is a particularly suitable area to study past global climate changes and their influence on locale Human settlements. A paleohydrological investigation was therefore carried out on two river-fed lakes: Lake Qallimiut and Little Kangerluluup, both located close to the Labrador Sea in the historic farming center of Greenland. Two sediment cores (QAL-2011 and LKG-2011), spanning the last four millennia, were retrieved and showed similar thin laminae, described by high magnetic susceptibility and density, high titanium and TOC / TN atomic ratio, and coarse grain size. They are also characterized either by inverse grading followed by nor…

The karstic aquifer of Lake Antre (Jura Mountains - France): an anthropic control since the first century A.D.?

Sediment yield from glacio-lacustrine calcareous deposits during the postglacial period in the Combe d’Ain (Jura, France)

The middle valley of the river Ain (Jura) cuts through glacio-lacustrine deposits laid down in an ice-dammed lake during the most recent glacial advance. The total volume eroded is about 6·21 ×10 8 m 3 for a surface area of 3·7 ×10 7 m 2 . Erosion occurred between 18 ka BP and 6 ka BP, i.e. over a duration of some 12 ka. Sediment yield from the area was of the order of 2500 t km -2 a -1 , which is comparable with modern-day sediment yield from NW African badlands. These high values are ascribed to the amenability of glacio-lacustrine deposits to mechanical weathering and to the rapid geomorphological changes that affected glacial and paraglacial sedimentary cover after the retreat of the ic…

Chupicuaro archaeological sites: from magnetic survey to excavation (Late pre-classic period, Middle Lerma Valley, Mexico)

Variations in sediment yield from the Upper Doubs River carbonate watershed (Jura, France) since the Late Glacial Period

International audience

Un déboisement par le feu du littoral de Chalain (Jura, F) pour l’exploitation agro-pastorale à l’époque carolingienne :caractérisation géo-archéologique et paléo-environnementale d’une « anomalie » pédo-sédimentaire.

International audience

Cartographie géologique à haute résolution pour une meilleure compréhension de la diversité du sous-sol viticole de la " Côte " (Bourgogne, France)

International audience

Les sites ecclésiaux et monastiques de l’archipel du Kvarner (Croatie)

La campagne 2016 du programme de recherche sur les sites ecclésiaux et monastiques de l’archipel du Kvarner a essentiellement porté sur la fouille du petit complexe antique et médiéval septentrional du site de Mirine-Fulfinum – secteur dit de « l’église à trois absides » – (île de Krk), du 11 au 23 avril 2016, et sur la poursuite de la fouille de la grande église paléochrétienne du complexe de Martinšćica (île de Cres) du 27 juin au 14 juillet (fig. 1). Fig. 1 – Carte de l’archipel du Kvarner...

Sur les traces d'Erik le Rouge (film et conférence)

International audience

Magnetic survey on Chupicuaro's archaeological sites (late preclassic period, middle Lerma valley, Guanajuato - Mexico)

Première datation par chronologie radiocarbone du dernier maximum glaciaire dans le Jura

International audience

An Inverse Modeling Approach to Investigate Past Lead Atmospheric Deposition in Southern Greenland

International audience

L’hydrosystème karstique du sanctuaire gallo-romain du lac d’Antre et des sources de l’Héria.

National audience

Evolution des paysages Sahélines au cours des six dernières décennies dans la région de Niamey : de la disparition de la brousse tigrée à l'encroutement de surface des sols

In the Sahel, the rapid increase of the population during the last decades and the climate variation lead to an important environmental degradation. This work aims to measure the impacts of the human pressure on ecosystem during the six last decades. A diachronic cartography of a 100 km² area close to Niamey was done with aerial photographs (1950 and 1975) and GPS measurements (2009). Results showed that the tiger bush vegetation was completely cleared between 1950 and 2009 while the fallow decreases from 7 % to 1 %. In the sandy valley, the increase of cultivated fields from 20,7 % (1950) to 69,4 % (1975) favoured wind and water erosions which allowed surface soil crusting. Between 1975 an…

Landscape and Settlement Evolution during the Sixteenth Century: A multidisciplinary study of two mountain areas (Eastern France)

International audience

Vers l'Amérique : l'implantation médiévale scandinave de la côte sud-ouest du Groenland. Approches historiques et premiers résultats des études paléoenvironnementales

International audience; During the Viking Age (ca AD 800-1100) Scandinavian explorers settled the islands of the western North Atlantic, making the northernmost agricultural area of the medieval period. Expansion to south-west coast of Greenland at the end of the tenth century brought Norse settlers closer to the limits of their European-style agricultural systems. In response to the harsh low arctic climate, the Greenland Norse have adapted their farming strategies and changed their subsistence pattern, giving a more important place to hunting and fishing. This evolution had probably been accelerated by climatic changes of the Little Ice Age. A good knowledge of the Greenland Norse economy…

The hydrothermal carbonated complexes in the Acambaro Valley: precolumbian and modern human impacts

The history and impacts of farming activities in south Greenland: an insight from lake deposits.

International audience; Agriculture in southern Greenland has a two-phase history: with the Norse, who first settled and farmed the region between 985ad and circa 1450ad, and with the recent reintroduction of sheep farming (1920ad to the present). The agricultural sector in Greenland is expected to grow over the next century as anticipated climate warming extends the length of the growing season and increases productivity. This article presents a synthesis of results from a well-dated 1500-year lake sediment record from Lake Igaliku, south Greenland (61°00′N, 45°26′W, 15m asl) that demonstrates the relative impacts of modern and Norse agricultural activities. Pollen, non-pollen palynomorphs…

Towards America: environmental consequences of the Viking occupation in Greenland.

A 2500 year record of natural and anthropogenic soil erosion in South Greenland

International audience; The environmental impact of the Norse landnám in Greenland has been studied extensively. But to date, no study has quantified the soil erosion that Norse agricultural practices are believed to have caused. To resolve this problem, a high resolution sedimentary record from Lake Igaliku in South Greenland is used to quantitatively reconstruct 2500 years of soil erosion driven by climate and historical land use. An accurate chronology allows for the estimation of detritic fluxes and their uncertainties. Land clearance and the introduction of grazing livestock by the Norse around 1010 AD caused an acceleration of soil erosion up to 8 mm/century in 1180 AD which is two-fo…

Variations in Sediment Yield from the Upper Doubs River Carbonate Watershed (Jura, France) since the Late-Glacial Period

AbstractThe Upper Doubs River Valley is a 910-km2watershed feeding into Lake Chaillexon. The lake was formed by a natural rockfall at the end of the Bølling Chronozone (around 14,250 cal yr B.P.) and since then has trapped material eroded from the watershed. The filling process and variations in sediment yield have been investigated by mechanical coring, seismic surveys, and electric soundings. The detrital sediment yield of the upstream watershed can be calculated by quantifying the sedimentary stocks for each climatic stage of the Late-Glacial period and Holocene Epoch and estimating the lake's entrapment capacity. This enables us to determine the intensity of the erosion processes in rel…

Historical mining and smelting in the Vosges Mountains (France) recorded in two ombrotrophic peat bogs

Two peat sequences were sampled in the vicinity of the main mining districts of the Vosges Mountains: Sainte-Marie-aux-Mines and Plancher-les-Mines. Lead isotopic compositions and excess lead fluxes were calculated for each of these radiocarbon-dated sequences. Geochemical records are in very good agreement with the mining history of the area, well known over the last millennium. Except for an anomaly corresponding to the Middle Bronze Age which has not yet been resolved, there is no clear geochemical evidence of local metal production in the Vosges before the 10th century as excess lead deposition archived between 500 BC and 500 AD is attributed to long-range transport of polluted particul…

The impact of Norse occupation in south Greenland: pollen, NPP's and sedimentological analyses from lakes and peat deposits.

Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers

Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…

Montagnes du Jura, géologie et paysages

Environmental consequences of the Norse occupation in south Greenland: first results of pollen and NPP's data from a peat bog (Qassiarsuk).

Spatial characterization of leachate plume using electrical resistivity tomography in a landfill composed of old and new cells (Belfort, France)

International audience; Located near Belfort (France), the Etueffont landfill was in operation from 1976 to 2002 for the disposal and storage of domestic waste produced by 47,650 inhabitants. The site is comprised of the original landfill site called the old landfill (OL), in operation from 1976 to 1999, and a newer section known as the new cell (NC) which operated from 1999 to 2002. The objective of this study is to determine, using electrical resistivity tomography (ERT), the extent of the leachate plume from the OL and to monitor the efficiency of the liner of the NC. The entire Etueffont site was crisscrossed with 21 electrical profile lines which were traced in summer between 2009 and …

Pollen and non-pollen palynomorph evidence of medieval farming activities in southwestern Greenland

International audience; Radiocarbon dating, pollen and non-pollen palynomorph analyses from a lake core were used to establish the timing and effects of farming activities around Lake Igaliku, Eastern Settlement, Greenland. The absence of agro-pastoral impact before the medieval colonization by Europeans provides an opportunity to understand the development of farming activity in a pristine landscape. The results show that the first phase of clearance and grazing pressure, without the expansion of the Norse apophyte (native plant, in habitats created by humans) Rumex acetosa type, could have occurred in the 9–10th century A.D. The presence of Norse settlers and livestock is clearly recorded…

Au Niger, un paysage sahélien façonné par l'homme

National audience

Identification des indices environnementaux d'anthropisation dans la séquence sédimentaire historique du lac d'Igaliko (Groenland)

Tiempos de crisis y cambios socioculturales en Chupicuaro al final del Preclásico: evidencias paleoambientales e indicadores arqueológicos en el valle de Acámbaro, Guanajuato, México

International audience; "Los trabajos realizados en el valle de Acámbaro evidenciaron para finales del Preclásico (hacia 100 a.C.), una serie de cambios que denota un tiempo de crisis y de transición. El estudio revela una reducción drástica del número de sitios del Preclásico Terminal (fase Mixtlán: 1-250 d.C.), así como una nueva configuración espacial. Las excavaciones avalan las observaciones de superficie y comprueban que, a partir de 100 a.C., los asentamientos sufren una desocupación: en dos sitios excavados observamos estratos de abandono y luego de reocupación, y en los demás constatamos un abandono definitivo. Esta evolución parece coincidir con una baja demográfica. Los acontecim…

Monitoring soil volume wetness in heterogeneous soils by electrical resistivity. A field-based pedotransfer function.: A field-based pedotransfer function

11 pages; International audience; Modern irrigation techniques require accurate, rapid, cost-effective, spatial measurement of soil moisture. Electrical Resistivity Tomography (ERT) meets most of these requirements, but needs to be calibrated for each use because it is very sensitive to differences in soil characteristics. In this study, a pedotransfer function approach is used to remove the need for site-specific calibration, allowing ERT to be used directly to measure soil moisture. The study site was a hillslope vineyard, where eight calcaric-cambisol soil profiles were identified. From 2012 to 2013, 23 000 soil volume wetness measurements were acquired by Time Domain Reflectometry, and …

Long-term dynamics in microbial eukaryotes communities: a palaeolimnological view based on sedimentary DNA

International audience; Assessing the extent to which changes in lacustrine biodiversity are affected by anthropogenic or climatic forces requires extensive palaeolimnological data. We used high-throughput sequencing to generate time-series data encompassing over 2200 years of microbial eukaryotes (protists and Fungi) diversity changes from the sedimentary DNA record of two lakes (Lake Bourget in French Alps and Lake Igaliku in Greenland). From 176 samples, we sequenced a large diversity of microbial eukaryotes, with a total 16 386 operational taxonomic units distributed within 50 phylogenetic groups. Thus, microbial groups, such as Chlorophyta, Dinophyceae, Haptophyceae and Ciliophora, tha…

Contribution to the Holocene North Atlantic wind activity reconstruction from Lake Igaliku, South Greenland

International audience

Magnetic survey on Chupicuaro archaeological sites (late pre-classic period, Middle Lerma Valley, Guanajuato, Mexico)

Vers l'Amérique : l'implantation médiévale scandinave de la côte sud-ouest du Groenland

During the Viking Age (ca AD 800-1100) Scandinavian explorers settled the islands of the western North Atlantic, making the northernmost agricultural area of the medieval period. Expansion to south-west coast of Greenland at the end of the tenth century brought Norse settlers closer to the limits of their European-style agricultural systems. In response to the harsh low arctic climate, the Greenland Norse have adapted their farming strategies and changed their subsistence pattern, giving a more important place to hunting and fishing. This evolution had probably been accelerated by climatic changes of the Little Ice Age. A good knowledge of the Greenland Norse economy by means of historical …

Data from: Long-term dynamics in microbial eukaryotes communities: a paleolimnological view based on sedimentary DNA

Assessing the extent to which changes in lacustrine biodiversity are affected by anthropogenic or climatic forces requires extensive palaeolimnological data. We used high-throughput sequencing to generate time-series data encompassing over 2200 years of microbial eukaryotes (protists and Fungi) diversity changes from the sedimentary DNA record of two lakes (Lake Bourget in French Alps and Lake Igaliku in Greenland). From 176 samples, we sequenced a large diversity of microbial eukaryotes, with a total 16 386 operational taxonomic units distributed within 50 phylogenetic groups. Thus, microbial groups, such as Chlorophyta, Dinophyceae, Haptophyceae and Ciliophora, that were not previously co…