This study presents a tracer technique based on the fluorescent properties of quinine to help on the visualization of shallow flows and allow a quantitative measurement of overland flow velocities. ...Laboratory experiments were conducted to compare the traditional dye tracer and thermal tracer techniques with this novel fluorescent (quinine) tracer by injecting a quinine solution and the other tracers into shallow flowing surface water. The leading-edge tracer velocities, estimated using videos of the experiments with the quinine tracer were compared with the velocities obtained by using thermograms and real imaging videos of the dye tracers. The results show that the quinine tracer can be used to estimate both overland and rill flow velocities, since measurements are similar to those resulting from using other commonly used tracers. The main advantage of using the quinine tracer is the higher visibility of the injected tracer under ultraviolet A (UVA) light for low luminosity conditions. In addition, smaller amounts of quinine tracer are needed than for dye tracers, which lead to smaller disturbances in the flow. It requires a simple experimental setup and is non-toxic to the environment.
Changes in the climatology of precipitation and surface air temperature are being investigated worldwide, searching for changes in variability, the mean and extreme events (maximum and minimum). By ...exploring recent adjustments in the climate of mainland Portugal, particularly in the intensity, frequency and duration of extreme events, this study investigates trends in selected specific indices that are calculated from daily precipitation data from 57 and surface air temperature data from 23 measuring stations scattered across the territory. Special attention is paid to regional differences and variations in seasonality. The data cover the periods 1941–2007 for precipitation, and 1941–2006 for temperature. They are explored at the annual and seasonal scales and for different sub-periods.
Results show that trends in annual precipitation indices are generally weak and, overall, not statistically significant at the 5% level. Nevertheless, a decreasing trend is revealed by regional indices of total wet-day precipitation and extreme precipitation (above the 99th percentile). Seasonal precipitation exhibits significant decreasing trends in spring precipitation, while extreme heavy precipitation events, in terms of both magnitude and frequency, have become more pronounced in autumn. Results for winter and summer suggest that the extremes have not suffered any significant aggravation.
Trends for air temperature are statistically more significant and marked than for precipitation and indicate general warming across the territory. This warming trend is revealed very consistently by the time series of individual stations and regional mean temperature, and is also consistent with the findings reported in other studies for Portugal and at the European scale.
► We studied trends in climate indices of precipitation and temperature extreme events. ► The seasonality signal in both precipitation and temperature has become more intense. ► Heavy precipitation has decreased significantly in Spring and increased in Autumn. ► Partial trends analysis indicates strong warming after the mid seventies.
Around the world, growing energy consumption from rapid urbanization and industrialization together with the overwhelming reliance on fossil fuels is affecting the integrity of both natural and human ...systems. Additionally, rising oil and gas prices and potential future shortages lead to concerns about the security of the energy supply needed to sustain our economic growth. This has resulted in an increased awareness for environmental sustainability in all industrial sectors. In the agricultural sector, sugar crops processing for the production of sugar generates a wide variety of by-products. Their reuse represents a prime opportunity for value capture and for the sugar processing industry to be in the forefront of sustainability, while possibly realizing additional profits. Sugar crops such as sugarcane and sugar beets are versatile in that they include a rich sugar fraction (sucrose, syrups) in addition to fiber (cellulose), fodder (green and brown leaves and tops), fuel and chemicals (bagasse, molasses), and fertilizer (press mud). This is the first of two papers where production of several by-products is detailed together with their specific physicochemical properties and the ways in which they can be utilized beneficially and sustainably. In the second paper, state of the art value-added conversion technologies for these by-products are described in detail.
A series of activated carbons were used to investigate the photochemical behaviour of carbons under UV light as catalysts in the photo-oxidation of phenol in the absence of semiconductor additives. ...Conventional photocatalytic tests showed an improved photo-oxidation in the presence of activated carbons, beyond the so-called synergistic effect reported in the literature for carbon/titania composites. A novel approach based on UV irradiation of carbons pre-loaded with phenol was used to demonstrate the anomalous photochemical response of carbon materials towards phenol degradation. Analysis of the catalytic reaction from a different standpoint (inside the carbonaceous matrix) demonstrated the catalytic activity of certain carbon materials for phenol photodegradation, without considering photolytic breakdown and adsorption kinetics. The pseudo photochemical quantum yield of several activated carbons was higher than that of photolysis under the same conditions; the nature of the degradation intermediates was also modified in the presence of the carbon materials. Moreover, the degradation of the adsorbed fraction retained inside the pore structure of the carbons has been demonstrated. Our results suggest the occurrence of carbon–photon interactions which could be propagated through the graphene sheets of the materials, and could reach the adsorbed molecules inside the pores.
Sustainability of the sugar crops harvesting and processing industry is closely associated with valorization of its byproducts via conversion into beneficial bioproducts, biomaterials, biochemicals, ...and biofuels, with potential in agricultural, pharmaceutical, and industrial applications. Sugar crops are versatile in that they include a rich sugar fraction (sucrose, glucose, and fructose) in addition to fiber (cellulose, hemicellulose, and lignin). Byproducts such as leaves and tops can be used for fodder; bagasse and molasses for fuel and chemicals and press mud as fertilizer, and these encompass just a few examples of a myriad of applications. A detailed review of the state-of-the-art value-added conversion technologies for these byproducts is described in detail herein. Some technologies generate multiple co-products simultaneously, making the conversion more economically attractive and competitive toward traditional materials. There is also the opportunity for the creation of new jobs and markets for the dissemination of these products. In the first of two manuscripts, production of these byproducts is detailed together with their specific physicochemical properties and applications. This second manuscript is a review of the value-added conversion technologies for these byproducts.
This study aims mostly at understanding seasonal variations in the intensity, frequency and duration of extreme precipitation events in mainland Portugal. For this purpose, selected precipitation ...indices that mainly focus on extremes were calculated at the seasonal scale for daily data recorded in the period 1941–2007 at 57 meteorological stations scattered across the area. These indices were explored for trends at the local and regional levels. The results show that there are marked changes in precipitation indices at the seasonal scale. Trends in spring and autumn precipitation have opposite signals. In spring, statistically significant drying trends are found together with a reduction in extremes. In autumn, wetting trends are detected for all indices, although overall they are not significant at the 5 % level. In addition, the relationship between seasonal extreme precipitation indices and atmospheric large-scale modes of low-frequency variability is analysed by means of a seasonal correlation analysis. Four modes of low-frequency variability are explored. Results confirm that, over mainland Portugal, the North Atlantic Oscillation is one of the most important teleconnection patterns in any season and the mode of variability that has the greatest influence on precipitation extremes in the area, particularly in the winter and autumn.
Animal manure continues to represent a significantly large and problematic portion of the US agricultural waste generated yearly. Granular activated carbons made from pelletized poultry litter have ...been shown to adsorb various positively charged metal ions from laboratory-prepared solutions. The objective of this study was to develop a conceptual capital and operating cost estimate using the Superpro Designer process simulation program. In the study, it was assumed that the activated carbon manufacturing facility obtains the poultry litter from various farmers at a cost of $5.50 and $27.50
t
−1 for transportation. The carbon manufacturing facility processes 20
t of poultry litter per day and converts it into granular activated carbon for a final carbon yield of 21.6% (dry basis). This facility operates continuously, 330 days of the year. Several parameters were incorporated in the study including equipment sizing, capital costs and operating costs, such as labor, utilities, maintenance and equipment depreciation. The largest contributor to the cost of producing the activated carbon is the $1,200,000 equipment cost of the combined pyrolysis/activation furnace, which contributes about $0.47
kg
−1 to the production cost. This study indicates that activated carbon can be produced by this method at a cost of about $1.44
kg
−1.
Citral, 3,7-dimethyl-2,6-octadien-1-al, one of the main components of the essential oils obtained from several plants, is used as a food additive and as a fragrance for detergents, cosmetics and ...other toiletries. The literature shows disparity regarding citral genotoxicity. Thus, the main objective of our work was to evaluate the genotoxic effects of citral in human cell cultures, HepG2 and leukocytes. Cytotoxicity assays (trypan blue and MTT) showed citral toxic effects in HepG2 cells (with metabolizing liver enzymes), which contrasted with the absence of toxicity in leukocytes. After citral exposure, both cell types did not demonstrate clastogenic/aneugenic effects in the micronucleus test. However, for the comet assay, citral exposure lead to significant genotoxic effects in both HepG2 (even to citral low concentrations) and leukocytes. The use of citral must be viewed with caution due to its ability to induce DNA damages, especially after being metabolized by cells with active liver enzymes.
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