173 resultados para Viajes -- Guías


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Two sampling points were chosen and forty samples were collected between January and December 2006 at Alto Sorocaba basin. The rainwater pH varied from 5.46 to 6.36 (Ibiúna) and 5.26 to 6.81 (Itupararanga), being Ca2+ the main ion responsible for controlling the rainwater pH. The ionic concentrations decreased in the following order: Ca2 +>Na+> Mg2+>K+ for cations and SO4(2-)>HCO3->NO 3->Cl- >PO4(3-) for anions. The annual atmospheric deposition appeared to be controlled mostly by following sources: mining activities and cement factories (Ca2+ and HCO3-), natural soil dust (Na+, Mg2+ and HCO3-), fossil fuel burning (SO4(2-)) and agriculture activities (K+, NO3- and PO4(3-)).

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The objective this study was to monitor pesticide residues in groundwater at three different times and in seven regions producing rice in southern Brazil, in the 2007/08 season. Imazethapyr and fipronil were found in all regions studied. All groundwater samples from the Planície Costeira Interna to Lagoa dos Patos and Santa Catarina contained at least one pesticide. The lowest number of contaminated samples were detected in the Southern region. The highest frequency of contaminated samples was found after drainage of the rice fields. Only fipronil exceeded limits of potability, in 27% of samples, according European Community criteria.

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O Instituto, journal published by the Institute of Coimbra (IC), an academic society founded in this city in 1852, contains many articles on hydrology and chemical analysis of water for human consumption, written by well-known Portuguese chemists and physicians. Based on these papers, we analyse the evolution of hydrology in Portugal throughout the second half of the 19th century, with emphasis on the chemical studies of mineral waters by the physicians Augusto da Costa Simões, Francisco Alves and José Epifânio Marques, and by the chemists Joaquim dos Santos e Silva, António Ferreira da Silva and Charles Lepierre, all of them members of the IC.

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A preliminary analyses of the possible contamination of surface and groundwater by the active ingredients of the pesticide products used in the areas with intensive agricultural activities of Alto Paranaíba region, MG, Brazil, was carried out. The active ingredients and formulated products most used in the region were identified and their characteristics of environmental importance were presented. The EPA screening criteria, the groundwater ubiquity score (GUS) and the criteria proposed by Goss were used to evaluate which pesticides might contaminate the local waters. Among the active ingredients studied, several present risks to the local aquatic environment.

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Lead metallurgy at Adrianópolis is the largest environmental problem of Paraná, Brazil. The objective of this study was to determine Pb and Zn levels in water and sediment in two catchments by different extraction methods. The high levels of lead in water in most of samples do not allow the human use. Total Pb concentration as high as 795.3 µg L-1 was observed in Ribeira River bank, in a pluvial water stream flowering from a abandoned factory. Due to the high Pb levels in sediments from some sites (maximum of 24,300 mg kg-1) is recommended to avoid the water turbulence.

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This study validated a simple and applied method for determining mycotoxins aflatoxin B1, aflatoxin B2, ochratoxin A, zearalenone and deoxynivalenol, in water from the rice production chain. Five solvent combinations for extraction were tested, with quantification performed by TLC/HPTLC and confirmation by LC-MS/MS. Mycotoxins in water from field and rice industries were evaluated. Mycotoxin recovery levels were around 90%. Two samples from rice parboiling waste were contaminated (deoxynivalenol/aflatoxin B1, 110/9 ng mL-1; and deoxynivalenol, 100 ng mL-1). Zearalenone, deoxynivalenol and ochratoxin A (36, 30 and 28%) were carried to soaking water during parboiling.

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A multiresidue method using HPLC/DAD for the determination of fourteen pesticides in water based on SPE, using SDVB (styrene divynilbenzene copolymer) as adsorbent was validated. Recoveries from 61 to 120%, relative standard deviation between 2 and 15% and detection limits from 0.07 to 0.75 µg L-1 were obtained. It was applied to 66 surface water samples collected in a degraded area at the headwaters of São Lourenço river, Mato Grosso, Brazil. Eight pesticides were detected in concentrations ranging from 0.15 to 35.25 µg L-1. Considering ecotoxicological data, carbendazim and carbofuran may represent a risk to aquatic organisms. These results draw attention to the contamination of this vulnerable degraded area.

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Drugs of abuse are commonly used outside medical or legal settings where their production, marketing and consumption are subject to legal summons and/or intervention. Classified as emerging contaminants, these substances have been recently detected in samples of environmental concern, such as waters and wastewaters. This review presents the state-of-the-art on the methodological approaches used in sample preparation, the main techniques applied in analytical determination at trace levels, as well as the use of information related to the drug or its metabolite concentration in sewage samples to empirically estimate the consumption of drugs of abuse in a city or region.

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Two methods using headspace solid-phase microextraction and gas chromatography - mass spectrometry were developed for the determination of polycyclic aromatic hydrocarbons (PAH) and BTEX. Best results were obtained using DVB/CAR/PDMS fiber, with 10 min extraction at 25 °C and 0.15 min desorption at 260 °C (BTEX), and PDMS/DVB fiber, with 60 min extraction at 90 °C, 10% NaCl and 5 min desorption at 270 °C (PAH). LOD intervals were 3x10-2 - 5x10-2 µg L-1 (BTEX) and 1.6x10-3 - 1.4 µg L-1 (PAH). The methods were applied to forty-five groundwater samples from monitoring wells of gas stations and only benzene level exceeded the limit established by Brazilian regulations.

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A method was developed for the analysis of 31 pharmaceutical compounds in Lisbon's drinking water system, using solid-phase extraction (SPE) and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). The method was validated through estimation of the linearity range, method detection and quantification limits, matrix effects, precision and accuracy. The method detection and quantification limit ranges were 0.009-10 and 0.03-33 ng/L, respectively. Analytes were quantified in water samples collected from the EPAL (Empresa Portuguesa das Águas Livres S.A.) supply system. Carbamazepine, atenolol, sulfadiazine, sulfamethazine, sulfapyridine, sulfamethoxazole, acetaminophen, caffeine and erythromycin were quantified in the analysed samples.

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In this work, the efficiency of clarification treatment (coagulation, flocculation and sedimentation) with polyaluminum chloride (PAC) and aluminum sulfate (SA) as coagulants was evaluated in the removal of 7 microcontaminants (diclofenac - DCF, sulfamethoxazole - SMX, ethinylestradiol - EE2, bisphenol-A - BPA, estradiol - E2, estrone - E1 and estriol - E3) in water of low and high turbidity. The clarification treatment led to poor removal rates (40% at most) for all microcontaminants except SMX which exhibited intermediate removal efficiency (67 to 70%). Overall, PAC application yielded better performance compared to SA.

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New techniques for treating wastewater, particularly the removal or degradation of organic pollutants and heavy metals, among other pollutants, have been extensively studied. The use of nanostructured iron oxides as adsorbent and photocatalyst for the removal of these contaminants has proved a promising approach, not only because of their high treatment efficiency, but also for their cost-effectiveness, having the flexibility for in situ and ex situ applications. In this review, we briefly introduced the most used kinds of iron oxide nanoparticles, some synthesis techniques for iron oxide nanostructure formation, their potential benefits in environmental clean-up, and their recent advances and applications in wastewater treatment. These advances range from the direct applications of synthesized nanoparticles as adsorbents for removing toxic contaminants or as catalysts to oxidize and break down noxious contaminants (including bacteria and viruses) in wastewater, to integrating nanoparticles into conventional treatment technologies, such as composite photocatalytic filters (membranes, sand and ceramic) that combine separation technology with photocatalytic activity. Finally, the impact of nanoparticles on the environment and human health is briefly discussed.

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17α-methyltestosterone (17α-MT) is a hormone used in medicine and aquaculture which can be found in natural waters. It is considered an emerging organic pollutant and its accurate and precise analysis is required. Therefore, this study presents the in-house validation of a new voltammetric methodology for 17α-MT analysis in natural waters. A hanging mercury drop electrode and NaOH 5.0×10-3 mol L-1 solution as the electrolyte were employed in the voltammetric determinations. To confirm the presence of 17α-MT in water samples quantitative analysis was performed by ESI-MS/MS. The methodology exhibited good selectivity, linearity, accuracy (recovery of between 100.4 and 108.8%) and precision (RSDs for repeatability of 2.85% and for intermediate precision of 14.10%, with n = 5, respectively). LOD and LOQ were 3.07 µg L-1 and 10.78 µg L-1, respectively. The methodology was suitable for determination of 17α-MT in natural waters due to low-cost, good performance and no sample pre-treatment required.

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The present elaboration is a "previous note" about two watercourses, Maria Rodrigues and Baguaçú, belonging to Hydrografic System of the Cananeas Lagoon Region in the Southern Part of it he Coast of the Estado de São Paulo, Brazil, which is the objete of our physical and chemical researches. It is based on the first results obtained from our contact with that region, ttfie studies of which are being continued and will still have to confirm or not the previous conclusions, which we are presenting in this "provisional paper". We studied the Maria Rodrigues and the Baguacu under the discussion whether they are to be clasified as a river in the poper sense ot the word or waUer-courses of any other origin. For this purpose we established observatory-stations along their whole course where we collected quantities of water to be analised. The data included in the table nº 1 and 2 refer to the physical and chemical properties of these portions of water. These physical and chemical properties were discussed and compared one with the other according to the observatory-stations, at the same moment and the tide predominating on that occasion. The physical and chemical datas were obtained according to the norms recommended by the Conseil International permanent pour l'Exploration de la Mer, Copenhague. We also presented a sketch of both; we described their relations with regard to the Mar de Cananéia; we inserted comprehensible histograms of the distribution of the observatory-stations, each of them with the respective indices, and at last we tried to correlate the occurrence of the "plancton" with the physical and chemical properties of water as well in the Maria Rodrigues as in the Baguacú. From these researches result the following previous conclusions: 1 - By the data obtained up to now nothing could be formulated as to a cyclical or "seasonal" aspect. 2 - By the comparison of the phenomena which present the rivers in the proper sense of the word and those observed in the Maria Rodrigues and the Baguacú, we are convinced that both are water-courses of the classical type "marigot,". 3 - Their channels are maintained open by the effect of the tide and, more perphaps, by the infiltration-water deriving from the underground-water level owing to the type of the soil of that region, which in mean shows an elevation of 2-4 meters over sea-level. 4 - From tables 1 and 2 and histograms 2 and 3 we stated that the water, not only of the Maria Rodrigues but also of the Baguacú, conserve more or less the same physical and chemical properties, provided that: 1) the localities to be compared are the mouths or equidistant points from them in the lower course, and 2) the moment and tide must be the same. Tables 3a and 3b show sufficiently this supposition.