Correlation between the Flux Density and Polarization for Flat Spectrum Radio Quasars

In this paper, using the preliminary database of the University of Michigan Radio Astronomy Observatory (UMRAO) at the radio frequencies, we calculated the weighted polarization at 8 GHz and investigated the correlation between the polarization and the flux density for 92 flat spectrum radio quasars (FSRQs). We found that the two observations are closely and positively correlated for FSRQs. This is perhaps from a relativistic beaming effect.     

A methodological approach of fluvial dynamics oriented towards hydrosystem management: case study of the Loire and Allier rivers

Abstract

This study was conducted as part of the European LIFE Loire Nature program for the conservation and management of a 110-km-long section of the Loire and Allier rivers, an area renowned for its ecological richness. The methodological approach is based on statistical analysis (bivariate and multivariate analyses) of hydro-geomorphologic and biogeographical variables, complemented by reach typology and mapping. The main results show, on the one hand, the great spatial variability of fluvial mosaic complexity along the river continuum and on the other hand, some independence between the riparian forest characteristics and the channel forms. The fluvial pattern (e.g. anabranching) and the forest establishment along the Loire river register specific features. © 2000 Éditions scientifiques et médicales Elsevier SAS     

Longitudinal and temporal thermal patterns of the French Rh?ne River using Landsat ETM+ thermal infrared images

Understanding the thermal regime of rivers is a key issue for predicting ecosystem change in the context of global warming. However, water temperature is not only influenced by air temperature. To better highlight relative contribution of factors controlling water temperature, we used satellite thermal infrared (TIR) images from Landsat ETM+ to investigate longitudinal and temporal variations in thermal patterns of the French Rh?ne River. Because satellite TIR remote sensing is limited to large rivers, we used an automated water extraction technique to remove pixels contaminated by terrestrial surfaces. We calculated water surface temperatures of the 500?km long reach for 83 dates between 1999 and 2009. The average accuracy and uncertainty of our data, ±1.1 and ±0.4°C for reaches with more than 3?pixels across and ±1.4 and ±0.5°C for reaches with one to 3?pixels across, are comparable to other satellite TIR studies of rivers. Our results confirmed previous studies on the thermal impacts of tributaries and nuclear power plants on the Rh?ne, providing an understanding of their seasonal pattern and their longitudinal impact. We showed temperature differences of 0?C2°C within the largest hydroelectric bypass facilities between the bypass section and the canal, with Montélimar and Caderousse showing the most pronounced differences. Discussion points concern the potential impacts of tributaries and nuclear power plants on the spatio-temporal thermal patterns, as well as the factors responsible for thermal differences in the bypass facilities: length and minimum flow of the bypass section, and tributaries coming into this reach.     

Adsorption of Phosphate by Biomass Char Deriving from Fast Pyrolysis of Biomass Waste

Biomass char (BC) deriving from fast pyrolysis of biomass was a potential adsorption material due to its relative high fixed‐carbon content and the inherent porous structures. Adsorption of phosphate from aqueous solution by BC was investigated in this paper. The results showed that the adsorption capacity of BC was dependent on pyrolysis conditions, such as temperature and holding time. The maximum adsorption capacity for phosphate was approximately 15.11 mg g^?1 at 298 K. The pseudo‐second order model of the adsorption kinetics indicated that the adsorption process was complex and several mechanisms were involved. Equilibrium isotherm was satisfactorily followed the Freundlich isotherm model. The K_F value in Freundlich equation gradually increased with elevating temperature. Moreover, the thermodynamic constants: ΔG⁰, ΔH⁰, and ΔS⁰ were evaluated as ?6.49 kJ mol^?1 (at 298 K), 13.41 kJ mol^?1, and 66.70 J mol^?1 K^?1, respectively. Phosphate adsorption onto BC was spontaneous and endothermic. As a waste, BC was a potentially attractive adsorbent for phosphate removal from aqueous solution with low cost and high capability.     

Implementation and validation of video monitoring for wood budgeting in a wandering piedmont river,the Ain River (France)

The transport of wood in rivers during floods is an important process that underlies differences in habitat and morphology between water courses and regions. Quantitative data are needed to properly address management objectives and balance wood budgets. In this study we use a streamside video camera to detect wood passage and measure quasi‐instantaneous rates of wood transport in the Ain River, France. The objectives are to verify the procedure, describe the relation between wood transport and discharge, and construct and validate a wood budget for the reach upstream of the camera. Verification of the procedure includes tests of detection frequency, wood velocity, and piece size. A log base two transformation is proposed to classify wood by piece length. It was found that a wood transport threshold occurs at approximately two thirds of the bankfull discharge. Wood transport follows a positive linear relation with discharge up to the bankfull discharge but is both more variable and less sensitive to discharge when the floodplain is inundated. Transport rates are approximately four times higher on the rising limb of the hydrograph than on the falling limb. Wood transport estimates from a three‐stage rating curve are two to 10 times higher than those from a wood budget using local and aerial surveys of upstream dynamics. Future work should address uncertainties related to wood diameter measurements, sampling length and frequency, and antecedent floods. Copyright © 2012 John Wiley & Sons, Ltd.     

Mixed heavy metals tolerance and radial oxygen loss in mangrove seedlings

The effects of a mixture of heavy metals (Pb, Zn and Cu) on growth, radial oxygen loss (ROL) and the spatial pattern of ROL were investigated in mangrove seedlings of three species: Aegiceras corniculatum, Avicennia marina and Bruguiera gymnorrhiza. Heavy metals inhibited the growth of seedlings and led to decreased ROL and changes in the “tight” barrier spatial pattern of ROL. There was a significant positive correlation between the amount of ROL from the roots of seedlings and metal tolerance. The species with the highest ROL amount, B. gymnorrhiza, were also the most tolerant to heavy metals. The “tight” barrier spatial ROL pattern was also related to metal tolerance in the seedlings. Therefore, we conclude that both ROL amount and “tight” barrier spatial ROL pattern in the roots of the mangrove seedlings play an important role in resistance to heavy metal toxicity.     

Management alternatives to offset climate change effects on Mediterranean fire regimes in NE Spain

Fire regime is affected by climate and human settlements. In the Mediterranean, the predicted climate change is likely to exacerbate fire prone weather conditions, but the mid- to long-term impact of climate change on fire regime is not easily predictable. A negative feedback via fuel reduction, for instance, might cause a non-linear response of burned area to fire weather. Also, the number of fires escaping initial control could grow dramatically if the fire meteorology is just slightly more severe than what fire brigades are prepared for. Humans can directly influence fire regimes through ignition frequency, fire suppression and land use management. Here we use the fire regime model FIRE LADY to assess the impacts of climate change and local management options on number of fires, burned area, fraction of area burned in large fires and forest area during the twenty-first century in three regions of NE Spain. Our results show that currently fuel-humidity limited regions could suffer a drastic shift of fire regime with an up to 8 fold increase of annual burned area, due to a combination of fuel accumulation and severe fire weather, which would result in a period of unusually large fires. The impact of climate change on fire regime is predicted to be less pronounced in drier areas, with a gradual increase of burned area. Local fire prevention strategies could reduce but not totally offset climate induced changes in fire regimes. According to our model, a combination of restoring the traditional rural mosaic and classical fire prevention would be the most effective strategy, as a lower ignition frequency reduces the number of fires and the creation of agricultural fields in marginal areas reduces their extent.     

Heavy metal pollution in the soil surrounding a thermal power plant in Playas de Rosarito,Mexico

The generation of electricity has been identified as one of the main pollutant activities, and some studies have established an increment of heavy metals in soil in the areas surrounding these plants. The aim of this study was to evaluate the soil concentrations of heavy metals in the zone surrounding a thermoelectric power in Mexico. Thirty-two top soil samples (0–5 cm) were collected; additionally, four depth profiles (1 m) were investigated. Median concentrations for chromium, vanadium, nickel, mercury, and cadmium were 47, 47, 73, 0.02, and 0.01 mg/kg, respectively. Higher Cr, Ni, and V concentrations were observed in the soil depth profiles located closer to the plant in comparison with the concentrations found in the soil depth profile located further away from the plant; these results may indicate a possible accumulation of these metals. The geoaccumulation index results indicated that most of the sites were in the classifications of unpolluted and unpolluted to moderately polluted (classes 1 and 2). The statistical results showed that downwind of the plant in relation to the prevailing winds, there was a strong correlation between soil concentrations of chromium, copper, nickel, and vanadium. Based on the results of this study, it can be concluded that the use of fuel oil at the thermoelectric plant contributed to the accumulation of vanadium and nickel in the soil of the surrounding areas, as well as chromium and copper.     

Validation of joint inversion of direct current and electromagnetic measurements

One of the ways to improve the information content of a set of field data is that of combining the interpretation of disparate data sets. Electromagnetic and direct current resistivity methods suffer from inherent equivalence problem. Application of joint inversion for these measurements can overcome the problem of equivalence very well. In the present work, synthetic data from vertical electrical sounding (VES) and horizontal coplanar low-frequency induction sounding (EMHD) are inverted individually and jointly over different types of 1D earth structures. Global optimization with Monte Carlo Multistart algorithm was used in the calculations. The results obtained from the inversions of synthetic data indicate that the joint inversion significantly improves the solution reducing the ambiguity of the models.