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301.
Considering successive and costly increases in electricity rates, this article evaluates the generation of electricity from a photovoltaic system using solar energy, a renewable source. The solar photovoltaic system is installed at UNIVATES University Center, a public university in the state of Rio Grande do Sul, Brazil, and it is also connected to the electrical grid. Data related to the climatic conditions of the location, such as incident solar radiation, rainfall, and mean temperature, were obtained during the system's evaluation period and used along with bibliographic research on similar systems installed in southern Brazil. Our study quantified the energy produced over one calendar year (2014) and related it to the climatic variables and the conversion efficiency achieved by the system's photovoltaic modules. Our results show that there is both a strong relationship between the production of energy and climatic conditions and that the city, Lajeado, and the Brazilian state of Rio Grande do Sul, have good potential to supply energy using photovoltaic systems connected to the electrical grid. The horizontal global solar radiation average obtained in the study location was 4.14 kilowatts per square meter per day (kWh/m2/day), and the average monthly production of energy reached 243.93 kWh/m2/month, with a total of 2,927.10 kWh produced in 2014, achieving a monthly average conversion efficiency of 11.07%. This conversion efficiency is close to the value of 12.6% obtained in 2013 in a similar study of the same solar photovoltaic system conducted over a shorter time period.  相似文献   
302.
The aim of this research is to establish the processing factors of six pesticides durong the preparation of fresh-cut lettuce and to assess the risk of ingestion of pesticide residues associated with the consumption of the same. A field study was carried out on the dissipation of three insecticides (imidacloprid, tebufenozide, cypermethrin) and three fungicides (metalaxyl, tebuconazole, azoxystrobin) during treatment conditions simulating those used for commercial fresh-cut lettuce. A simultaneous residue analysis method is validated using QuEChERS extraction with acetonitrile and CG-MS and LC-MS/MS analysis. The residues detected after field application never exceed the established Maximum Residue Limits. The processing factors were generally less than 1 (between 0.34 for tebufenozide and 0.53 for imidacloprid), indicating that the process, as a whole, considerably reduces residue levels in processed lettuce compared to fresh lettuce. It is confirmed that cutting, followed by washing and drying, considerably reduces the residues. A matrix effect in the dialyzation of the pesticides is observed and the in vitro study of bioavailability establishes a low percentage of stomach absorption capacity (<15%). The EDI/ADI ratios found in all cases were well below their ADI values, and the dietary exposure assessed (EDI) in fresh-cut lettuce showed no concerns for consumer health.  相似文献   
303.
This study aimed to isolate and characterize bacteria able to use sulfentrazone in the commercial formulation as their sole carbon source. The isolation of the potential sulfentrazone-degrading bacteria was made from soil samples with a recent history of herbicide application and from isolates identified through rDNA sequencing. Subsequently, we assessed the growth of the isolates and their sulfentrazone degradation ability using high-performance liquid chromatography. Twenty-six potential sulfentrazone-degrading bacterial isolates were obtained in pure culture. Through analysis of the rDNA sequences, the predominance of bacterial species of the genus Pseudomonas was found. The isolates presented a differentiated ability of sulfentrazone degradation. The presence of herbicide in the culture medium reduced the log phase of four isolates. Pseudomonas putida, Pseudomonas lutea, Pseudomonas plecoglossicida and three isolates of Pseudomonas sp. showed higher sulfentrazone degradation capacity, which varied from 4 to 15%. This is the first report of the Pseudomonas genre capable of sulfentrazone degradation. The isolates obtained present potential use in bioremediation programs for soil contaminated with sulfentrazone.  相似文献   
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305.
In this study, we measured via surgical sampling hepatic EROD activity in yellow-legged gulls from oiled and unoiled colonies, 17 months after the Prestige oil spill. We also analyzed stable isotope composition in feathers of the biopsied gulls, in an attempt to monitor oil incorporation into marine food web. We found that yellow-legged gulls in oiled colonies were being exposed to remnant oil as shown by hepatic EROD activity levels. EROD activity was related to feeding habits of individual gulls with apparent consequences on delayed lethality. Capture-recapture analysis of biopsied gulls suggests that the surgery technique did not affect gull survival, giving support to this technique as a monitoring tool for oil exposure assessment. Our study highlights the combination of different veterinary, toxicological and ecological methodologies as a useful approach for the monitoring of exposure to remnant oil after a large oil spill.  相似文献   
306.
In this work, a statistical experimental design is performed in order to prepare CaCO3 materials for use as CaO-based CO2 sorbent precursors. The influence of different operational parameters such as synthesis temperature (ST), stirring rate (SR) and surfactant percent (SP) on CO2 capture is studied by applying Response Surface Methodology (RSM). The samples were characterized using different analytical techniques including X-ray diffraction, N2 adsorption isotherm analysis and Scanning Electron Microscopy–X-ray Energy Dispersive Spectroscopy (SEM-EDX). CO2 capture capacity was determined by means of a thermogravimetric analyzer which recorded the mass uptake of the samples when these were exposed to a gas stream containing diluted (15%) CO2. The statistical approach used in this work provides a rapid way of predicting and optimizing the main preparation variables of CaO-derived sorbents for CO2 sorption. The results obtained clearly indicate that four parameters statistically influence CO2 uptake: SR, the square of SR, its interaction with SP and the square of SP.  相似文献   
307.
308.

Introduction  

Arsenic (As) can be removed from water via rhizofiltration using phytostabilizing plants. The aim of this study was to investigate the performance of Eleocharis macrostachya in constructed wetland prototypes, as well as the plant's arsenic mass retention and the distribution of As along the wetland flow gradient and the soil in the wetland mesocosmos.  相似文献   
309.
A multiresidue method for the analysis of 86 persistent pollutants in marine sediments at ultra-trace level has been developed and validated using pressurized liquid extraction (PLE) and stir-bar sorptive extraction (SBSE) coupled with thermal desorption and gas chromatography-triple quadrupole mass spectrometry (TD-GC-MS/MS QqQ). The compounds analyzed belong to various families such as polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polybrominated diphenylethers, organophosphorus and organochlorine pesticides and other pesticides such as urons, and triazines. The analytes have very different polarities and log Kow values, which is an important parameter in the optimization of a SBSE method. Due to PLE high efficiency and throughput rates, along with the proven ability for multiresidue analysis and excellent sensitivity of SBSE, we present an efficient method. The limits of quantification obtained ranged from 0.014 to 1.0 ng g−1, with detection limits below pg g−1 levels. In order to validate the proposed methodology, quality parameters such as recovery, linearity and reproducibility were studied. Recoveries ranged from 63% to 119%, reproducibility (in terms of Relative Standard Deviation for ten determinations) was lower than 35% in all cases, and determination coefficients higher than 0.990 for all analytes. The main factors that affect PLE, SBSE and GC-MS/MS procedures were optimized. The method was applied to the analysis of nine marine sediments obtained from the nine main submarine wastewater discharge points (emissaries) presents along the coast of Tenerife Island (Canary Islands, Spain).  相似文献   
310.
Chemometrics are increasingly used in environmental monitoring studies, but are still far from being accepted as routine tools by field specialists. The multivariate character of usually highly correlated environmental data recommends the use of advanced chemometrics as part of the analytical methodology in order to get information on the basic structure of data. In this work, we have applied a battery of non-supervised (Principal Component Analysis (PCA)) and supervised (k-Nearest Neighbour (k-NN), Soft Independent Modelling of Class Analogies (SIMCA), Linear Discriminant Analysis (LDA) and Artificial Neural Networks (ANNs)) multivariate techniques on a specific environmental dataset. The dataset consists on the concentration of 14 elements (Al, As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, V and Zn) in 95 sediments collected at eight different locations of the estuary of the Nerbioi-Ibaizabal River (Bilbao, Basque Country) during 12 sampling campaigns conducted every 3 months between 2005 and 2008. The study aims to present a simple methodology of general applicability which may result in a flexible and practical tool to assess chemical pollution in sediments of a given specific site.  相似文献   
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