A Retrospective Isotopic Study of Spruce Decline in the Vosges Mountains (France)

The objective of this study was to assess the time variation of mineral and water stress levels across the life of a declining, Mg-deficient, spruce stand, in order to clarify the factors that caused the decline. Since 1985, strong soil acidification linked to a large leaching of nitrate and base cations was measured at the study site. In 1994, 5 trees were felled and tree rings were measured and analysed for Ca, Mg, K, Sr, ¹³C¹²C and ⁸⁷Sr/⁸⁶Sr isotopic ratios. Strontium pools and fluxes as well as root Sr isotope ratio in relation to depth were also measured. Wood chemical concentrations and isotope ratios were strongly related to the dominance status of each tree. On average during the study period, the ⁸⁷Sr/⁸⁶Sr ratio of spruce wood decreased. Using a mechanistic model computing long term variations of ⁸⁷Sr/⁸⁶Sr ratio in trees and soils, we reproduced the observed trend by simulating soil acidification – increasing Sr drainage from the whole profile, and particularly from the organic horizon –, and root uptake becoming more superficial with time. Between 1952 and 1976, tree ring ¹³C decreased strongly and continuously, which, in addition to other factors, might be related to an increase in water stress. Thus, a decrease in rooting depth, possibly related to soil acidification, appeared as a possible cause for the long term increase in water stress. The extreme drought event of 1976 appears to have revealed and triggered the decline.     

Croissance de la larve de l'oursin Paracentrotus lividus

Paracentrotus lividus (Lamarck) larvae were reared to metamorphosis. The larvae were fed on the haptophycean Hymenomonas elongata Droop (Braarud) at three concentrations: 9 to 14×10⁵, 24 to 37×10⁵, 43 to 61×10⁵ μm³ cells ml^-1 d^-1. Optimum growth took place at a density of 24 to 37×10⁵ μm³ algal cells. Growth of the plutei was estimated in terms of weight increases in protein, carbohydrate and lipid; growth equations are given. The relationship between growth and the food ingested was calculated for the different larval stages. Earlier field data for the bay of Villefranche have shown the mean biovolume of nanoflagellates to be 0.65×10⁵ μm³ ml^-1; at such in situ food concentrations, P. lividus larvae would metamorphose only after one month of planktotrophic life. Chemoreception by larvae could lead to prey selection, thereby altering the amounts of protein, carbohydrate and lipid ingested, and hence the duration of larval life.     

Sterols in sediment samples from Venice Lagoon, Italy

Sterols of different origin were analysed in sediment samples collected in the Venice Lagoon. The purpose of the study was to investigate the degree of sewage contamination within the Lagoon using fecal sterols (coprostanol, epicoprostanol and coprostanone) and to analyse the pattern of the sterols to plot the origin of the organic matter.

Sedimentary coprostanol at Canal Grande within the city of Venice was more than one order of magnitude higher than other stations in the Lagoon and two orders higher than in a sediment sample collected in the open sea. The cholesterol/coprostanol ratio, like the percentage of coprostanol in total sterols at this sample site was very similar to values in sewage sludge. The different pattern of sterols at station 2 which had the largest amount of total sterol indicates a difference in the origin of the organic material. Nevertheless the sterols used as tracer of terrestrial vascular plants did not show any particular trend at this station, receiving fresh water inputs. (3-Sitosterol and cholestanol reached the highest levels at the station within the Chioggia basin.     

Advanced techniques in air pollution†

Specific usage of neutron activation analysis, charged particle analysis, y photons analysis, G.C.M.S. coupling, stable isotope dilution techniques, are discussed.

Dust collected on filters, oxygenated compounds in exhaust gases from car engines, nitrogen oxides, have thus been determined.

Special calibration methods for ozone, and remote detection by Lidar Raman are also described.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

Production of zeolitic materials in pilot scale based on coal ash for phosphate and potassium adsorption in order to obtain fertilizer

Environmental Science and Pollution Research - The use of different types of zeolites (X, Na-P1, and 4A) synthesized by different methods and scales were tested in this work to adsorb nutrients...     

Connectivity of Hybrid Polymer by Tight Binding Approximation: Example of (Si(CH3)2) n (OSiO) p (OH) q

We computed by a tight binding calculation taking into account hybridization, the total electronic energy of different connectivities (amorphous, fractal and linear) of (Si−(CH₃)₂) _n −(OSiO) _p (OH) _q . We found that the total electronic energy of the amorphous connectivity was the smallest as a function of the number of atoms contained by the hybrid polymer. As the total electronic energy is linked to the stability, we may say that the connectivity of such hybrid polymer has the highest stability for the amorphous connectivity.     

Outdoor air pollution in close proximity to a continuous point source

Data are lacking on human exposure to air pollutants occurring in ground-level outdoor environments within a few meters of point sources. To better understand outdoor exposure to tobacco smoke from cigarettes or cigars, and exposure to other types of outdoor point sources, we performed more than 100 controlled outdoor monitoring experiments on a backyard residential patio in which we released pure carbon monoxide (CO) as a tracer gas for continuous time periods lasting 0.5–2 h. The CO was emitted from a single outlet at a fixed per-experiment rate of 120–400 cc min^?1 (～140–450 mg min^?1). We measured CO concentrations every 15 s at up to 36 points around the source along orthogonal axes. The CO sensors were positioned at standing or sitting breathing heights of 2–5 ft (up to 1.5 ft above and below the source) and at horizontal distances of 0.25–2 m. We simultaneously measured real-time air speed, wind direction, relative humidity, and temperature at single points on the patio. The ground-level air speeds on the patio were similar to those we measured during a survey of 26 outdoor patio locations in 5 nearby towns. The CO data exhibited a well-defined proximity effect similar to the indoor proximity effect reported in the literature. Average concentrations were approximately inversely proportional to distance. Average CO levels were approximately proportional to source strength, supporting generalization of our results to different source strengths. For example, we predict a cigarette smoker would cause average fine particle levels of approximately 70–110 μg m^?3 at horizontal distances of 0.25–0.5 m. We also found that average CO concentrations rose significantly as average air speed decreased. We fit a multiplicative regression model to the empirical data that predicts outdoor concentrations as a function of source emission rate, source–receptor distance, air speed and wind direction. The model described the data reasonably well, accounting for ～50% of the log-CO variability in 5-min CO concentrations.     

Estimating an homogeneous series of a population abundance indicator despite changes in data collection procedure: A hierarchical Bayesian modelling approach

Abundance indicators are required both to assess and to manage wild populations. As new techniques are developed and teams in charge of gathering the data change, data collection procedures (DCPs) can evolve in space and time. How to estimate an homogeneous series of abundance indicator despite changes in DCP? To tackle this question a hierarchical Bayesian modelling (HBM) approach is proposed. It integrates multiple DCPs in order to derive a single abundance indicator that can be compared over space and time irrespective of the DCP used. Compared to single DCP models, it takes further advantage for abundance estimation of the joint treatment of a larger set of spatio-temporal units. After presenting the general formulation of our HBM approach, it is applied to the juvenile Atlantic salmon (Salmo salar L.) population of the River Nivelle (France). Posterior model checking, using χ² discrepancy measure, do not reveal any inadequacy between the model and the data. Despite a change in the DCP used (successive removals to catch-per-unit of effort), a unique abundance indicator for the 425 spatio-temporal units (site × year) sampled over twenty-four years (1985-2008) is estimated. The HBM approach allows the assessment of precision of the abundance estimates and shows variation between DCPs: a reduction in precision is observed during the most recent years (2005-2008) when only the catch-per-unit of effort DCP was used. The merits and generality of our HBM approach are discussed. We contend it extends previous single DCP models or inter-calibration of two DCPs, and it could be applied to a wide range of specific situations (taxon and DCPs).