Search results for "Environmental engineering"
showing 10 items of 2674 documents
Rainfall timing and runoff: The influence of the criterion for rain event separation
2016
Abstract Rain is not uniform in time and space in semiarid areas and its distribution is very important for the runoff process. Hydrological studies usually divide rainfall into events. However, defining rain events is complicated, and rain characteristics vary depending on how the events are delimited. Choosing a minimum inter-event time (MIT) is a commonly used criterion. Our hypothesis is that there will be an optimal MIT that explains the maximum part of the variance of the runoff, with time to runoff used as a surrogate. The objective is to establish a procedure in order to decide upon this optimal MIT. We developed regressions between time to runoff (T0) and three descriptive variable…
Thematic Issue on Soil Water Infiltration
2017
Interpretive Summary: When water is applied to the land surface through irrigation or rainfall, it infiltrates into the soil surface and percolates deeper through the soil profile under the influence of gravity and capillary forces. Soil infiltration is one of the most complex processes within the terrestrial hydrologic cycle, yet the process is only partially understood. Infiltration is affected by the physical, chemical and biological properties of the soil, vegetation cover, rainfall, irrigation properties, and management practices. Measurement of infiltration rate is essential in studies concerning water budget, hydrology, runoff, erosion, irrigation, drainage and water conservation. Ho…
Determination in situ of the size distribution of the atmospheric aerosol
1975
Abstract The aim of the present study was the investigation of the in situ number/size distribution of the atmospheric aerosol in the size range between 0·05 and 2 μm radius. The experimental system consisted of a 4-channel integrating nephelometer, a 2-channel optical particle counter and a condensation nucleus counter. With a new inversion method, which had been tested previously by model computations and by measurements with artificial aerosols, the in situ size distribution was computed from the data of the experimental system.
Stochastic multicriteria evaluation of district heating systems considering the uncertainties
2018
It is of great importance to choose a suitable district heating (DH) system for a specific DH area from the economics, environment and energy (3E) points of view. This is a multicriteria decision making problem, in which the criteria performance values (PVs) and weighting are characterized by uncertain or imprecise information. In this study, seven candidate DH systems are evaluated from the viewpoints of 3E by the stochastic multicriteria acceptability analysis (SMAA) method. SMAA is able to handle the uncertainties of the criteria PVs and the weighting at the same time. These uncertainties are very common and typical in real-life, but in most cases are not treated judiciously or just negl…
Analysis of a severe pollution episode in Valencia (Spain) and its effect on ground level particulate matter
2013
Abstract This study analyzes the atmospheric particles concentration at ground level during a severe pollution event that took place in Valencia (Spain) from 7 to 12 February 2011. The episode was related to a subtropical anticyclone system that affected the Iberian Peninsula and western Europe. The dominant anticyclone imposed an extended low gradient pressure system and a low mixing layer height in the region that caused the accumulation of pollutants over the western Mediterranean. Moreover, the stagnant conditions led to the formation of the local sea breeze, accompanied by an increase of relative humidity and the decrease of ambient temperature. Our study is mainly focused on the analy…
Deterioration of Property of Aluminum Alloys (EN AW-1050A, EN AW-5754 and EN AW-6060) by Absorbed Hydrogen
2022
The paper reports the results of research on the effect of hydrogen penetration on the variations in the mechanical properties of selected aluminum alloys. As a result of the study, it can be observed that such variations contribute to the deterioration of mechanical properties, which, in turn, contributes to shortening the reliability time associated with the operation of aluminum alloy structures. The analysis involved structural aluminum alloys: EN AW-1050A, EN AW-5754 and EN AW-6060. Tensile strength and impact strength were measured. It was demonstrated that the absorption of hydrogen by the analyzed alloys led to the deterioration of mechanical properties of aluminum alloys. The perfo…
Distribution and fate of perfluoroalkyl substances in Mediterranean Spanish sewage treatment plants.
2014
The concentrations of 21 perfluoroalkyl substances (PFASs: C4-C14, C16, C18 carboxylates, C4, C6-C8 and C10 sulfonates and C8 sulfonamide) were determined in influent, effluent and sludge from 16 different sewage treatment plants (STPs) located in the Ebro (6), Guadalquivir (5), Jucar (2) and Llobregat (3) Rivers, in two consecutive years (2010 and 2011). The analytes were extracted by solid phase extraction (SPE) and determined by Liquid Chromatography triple Quadrupole Mass Spectrometer (LC-QqQ-MS). All samples, except two sludges from Guadalquivir River STPs, were contaminated with at least one PFAS. Perfluorobutanoate (PFBA), perfluoropentanoate (PFPeA) and perfluorooctane sulfonate (L-…
Monitoring of persistent organic pollutants in the polar regions: knowledge gaps & gluts through evidence mapping
2017
Persistent organic pollutants (POPs) are widespread compounds that accumulating in polar regions canalise through trophic webs. Although several dozens of studies have been carried out in the last decades, the information is generally scattered across a large number of literature sources. This does not allow an efficient synthesis and constraints our understanding on how address future monitoring plans and environmental conservation strategies on the Polar Regions with respect to POPs. Thus, here, we present the outcome of a systematic map (SM) to scope, screen and chart evidences from literature dealing with POPs in Polar regions. The SMs strive to produce rigorous guidelines and have rece…
Trophic transfer of polychlorinated biphenyls (PCB) in a boreal lake ecosystem: Testing of bioaccumulation models
2013
Understanding the fate of persistent organic chemicals in the environment is fundamental information for the successful protection of ecosystems and humans. A common dilemma in risk assessment is that monitoring data reveals contaminant concentrations in wildlife, while the source concentrations, route of uptake and acceptable source concentrations remain unsolved. To overcome this problem, different models have been developed in order to obtain more precise risk estimates for the food webs. However, there is still an urgent need for studies combining modelled and measured data in order to verify the functionality of the models. Studies utilising field-collected data covering entire food we…
Assessment of the efficacy of Artemia sp (Crustacea) cysts chorion as barrier to chlorpyrifos (organophosphorus pesticide) exposure. Effect on hatchi…
2005
In order to reveal the efficacy of the Artemia cysts chorion as barrier to the organophosphorus pesticide chlorpyrifos, whole and decapsulated cysts have been exposed to 10 mg L(-1) chlorpyrifos in sea water during hydration and hatching phase, separately. The concentration of chlorpyrifos in capsulated and decapsulated cysts after exposure has been determined in order to elucidate the efficacy of chorion as protection to the embryo. The results obtained demonstrate the ability of the cysts chorion to obstruct the pass of chlorpyrifos molecules through this protection structure. Thus, the concentration of chlorpyrifos in exposed decapsulated cysts is higher than in exposed whole cysts. More…