Search results for " life"

Evidence of organic contamination in urban soils of Cotonou town (Benin).

2012

14 pages; International audience; In Cotonou (Benin), growth of the population leads to an excessive use of natural resources, inducing organic contaminations. Surface soils collected in the town, were extracted and fractionated by liquid chromatography in three families: aliphatic, aromatic hydrocarbons and polar fractions. Each fraction was characterized by gas chromatography-mass spectrometry. All the results show that an anthropogenic input exists (waste oils). Indeed, aliphatic hydrocarbons have specific markers emphasizing the presence of petrogenic products: UCM (unresolved complex mixture), specific distribution of pentacyclic triterpane. However, specific molecular biomarkers revea…

Soil moisture modelling of a SMOS pixel: interest of using the PERSIANN database over the Valencia Anchor Station

2010

In the framework of Soil Moisture and Ocean Salinity (SMOS) Calibration/Validation (Cal/Val) activities, this study addresses the use of the PERSIANN-CCS<sup>1</sup>database in hydrological applications to accurately simulate a whole SMOS pixel by representing the spatial and temporal heterogeneity of the soil moisture fields over a wide area (50×50 km<sup>2</sup>). The study focuses on the Valencia Anchor Station (VAS) experimental site, in Spain, which is one of the main SMOS Cal/Val sites in Europe. <br><br> A faithful representation of the soil moisture distribution at SMOS pixel scale (50×50 km<sup>2</sup>) requires an accurate estimation…

Trace element behaviour in seawater during Etna's pyroclastic activity in 2001: Concurrent effects of nutrients and formation of alteration minerals

2010

volcanic ash ; trace element leaching ; kinetic experiments ; chlorophyll-alpha; International audience; The eruption of Etna in Sicily on 13 July 2001 marked the most intense activity of the volcano in the last 300 years. The eruption occurred while the oceanographic cruise ANSIC 01 was being conducted to the east of Sicily, presenting a unique opportunity for the investigation of the chemical effects on the marine system during a period of significant (similar to 1 g m(-2)) ash deposition. Comparison of trace element data with measured concentrations from the oceanographic cruise JUVENILE 99, carried out two years before, indicates large enrichments of V. Cr, Mn, Fe, Co, Cu and Pb. We att…

Monitoring elevation variations in leaf phenology of deciduous broadleaf forests from SPOT/VEGETATION time-series

2011

International audience; In mountain forest ecosystems where elevation gradients are prominent, temperature gradient-based phonological variability can be high. However, there are few studies that assess the capability of remote sensing observations to monitor ecosystem phenology along elevation gradients, despite their relevance under climate change. We investigated the potential of medium resolution remotely sensed data to monitor the elevation variations in the seasonal dynamics of a temperate deciduous broadleaf forested ecosystem. Further, we explored the impact of elevation on the onset of spring leafing. This study was based on the analysis of multi-annual time-series of VEGETATION da…

Textural-chemical changes and deformation conditions registered by phyllosilicates in a fault zone (Pic de Port Vieux thrust, Pyrenees)

2017

International audience; Synkinematic phyllosilicates in fault zones can be used to deduce the deformation mechanisms and the conditions of fault activity, as their chemical composition, crystal structure and texture can record the different stages of deformation and fluid-rock interactions. The Pic de Port Vieux, a second-order thrust related to the major Gavarnie thrust in the southern central part of the Pyrenees Axial Zone, juxtaposes Triassic pelites of the hanging wall and Cretaceous limestones of the footwall. In order to investigate the mineralogical and geochemical changes and constrain the deformation conditions of thrusting, characterization of phyllosilicates was performed along …

Simulation of nitrous oxide emissions from wheat-cropped soils using CERES

2005

Estimation of nitrous oxide (N2O) emissions from arable soils, in relation to crop fertilization, is essential to devise strategies to mitigate the impact of agriculture on global warming. This paper presents the development and test of a N2O model resulting from the linkage of a dynamic soil-crop simulation model (CERES) with two sub-models of N2O production and reduction in soils. These sub-models (NOE and NGAS) account for both the nitrification and denitrification pathways. The resulting models (CERES–NOE and CERES–NGAS) were tested against experimental data collected on three contrasting wheat-cropped soils representative of the Beauce agricultural region in France. Although the input …

A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves

2021

Abstract: A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geographic focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concentrations within the High Risk Category (H…

Soil erosion in sloping vineyards assessed by using botanical indicators and sediment collectors in the Ruwer-Mosel valley

2016

Steep slopes, erodible soils, rill and ephemeral gullies, compaction due to wheel. traffic and human trampling are common features in vineyards around the world and result in high soil erosion rates. However, little is known about seasonal and spatial variations of soil erosion rates due to factors such as the impact of the vine plantation, harvest, and tillage on the soil redistribution over the long-term temporal scale. The goal of this study is to assess long-term soil erosion rates and the impact of management on sediment and runoff yield by means of Gerlach troughs and a topographical approach based on botanic benchmarks in two paired vineyards with different ages (3 and 35 years) loca…

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…

2017

Abstract. Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple en…