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- Hydrogeochemical, isotopical and ecotohicological approach to the Paranhos spring galleries catchworks from Porto urban area (nw Portugal)Publication . Guimarães, Laura; Afonso, Maria José; I. Chaminé, Helder; Marques, José M.; Carreira, Paula; Costa, Isilda; Teixeira, José; Guilhermino, Lúcia; Carvalho, José Martins; Fonseca, Paulo E.; Rocha. Fernando T.; Beleza, VitorinoThis multidisciplinary study presents the preliminary results of the hydrogeochemical, isotopical and ecotoxicological analyses performed to assess the nature and suitability for use of groundwater from the Paranhos’ spring galleries catchworks. These springs constituted for more than five centuries one of the main water supplies to Porto city. For the characterisation of the underground area (ca. 3km extension and a-25m of depth), constituted mainly by granitic rocks, the following tools were applied: i) subsurface geological and geotechnical mapping and; ii) hydrogeological, isotopical and ecotoxicological techniques. Surface and subsurface fieldwork surveys were first carried out to identify major tectonic accidents responsible for groundwater circulation paths and to assess lithological and structural heterogeneity. Hydrogeological fieldwork campaigns were then performed, and in situ determinations included: temperature (°C), pH and electrical conductivity (uS/cm). Several sampling sites were subsequently established, based on the surface activities located on the course of the springs, and water samples were collected for hydrogeochemical, isotopical and ecotoxicological analyses. All the water samples have been analysed for major element concentration. The isotopic techniques employed included d2H and d18O. For ecotoxicological evaluation standard acute bioassays with Daphnia magna were performed. For each sample, two 48h-LC5o bioassays were simultaneously performed: one with PH correction and the other without pH correction. In each bioassay, five concentrations of groundwater were prepared by dilution of the original sample with ASTM hard water. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, probably resulting from intense urbanisation, sewer leakage and some agricultural practices. Concerning the ecotoxicological analyses, no mortality was observed in any of the tests performed. The results obtained in this study suggest that part of Porto urban groundwater could be suitable for irrigation uses, but additional tests must be carried out to verify its compliance with existing standards of water quality. Specifically, geoenvironmental and ecotoxicological studies are required to assess potential variations in water composition and toxicity associated with seasonal changes in climate and human activities.
- A preliminary hydrogeologic conceptual model of the Manteigas-Nave de Santo Antonio-Torre sector (Serra da Estrela Natural park, central Portugal)Publication . Marques, Jorge Espinha; Marques, José M.; Carreira, Paula M.; I. Chaminé, Helder; Fonseca, Paulo E.; Samper, Javier; Pisani, B.; Alvares, D.; Vieira, Gonçalo T.; Mora, Carla; Teixeira, José; Gomes, Alberto; Carvalho, José Martins; Borges, Frederico S.; Rocha, Fernando T.; Beleza, VitorinoThis work is strongly connected with one of the most crucial water research issues at the turn of the millennium “High Mountain Areas Hydrology” (UNESCO IHP-VI Programme). Special emphasis is dedicated to high mountains and their role and impact on surface water/groundwater interaction at Serra da Estrela region - Central Portugal, in order propose a preliminary hydrogeologic conceptual model of the Manteigas - Nave de Santo Antonio - Torre sector, contributing to i) increase knowledge on recharge and discharge processes in this high mountain area and ii) assess the role of snowmelt as a source of groundwater resources, with the aid of coupled isotopic and geochemical techniques. The isotopic signatures of Caldas de Manteigas thermomineral waters combined with the i) morphostructural data and ii) isotopic composition of shallow groundwater and precipitation samples, made it possible to identify possible recharge areas, which should be located at altitude sites above 1500 m a.s.l.. The recharge altitudes are similar to those of Nave de Santo Antonio area which is directly located on the Braganca-Vilarica-Manteigas fault zone. This tectonic structure should play an important role in groundwater recharge and circulation towards the discharge zone at the Spas.
- Studies of particulate fouling for a water-kaolin suspension flowing in a horizontal square section channelPublication . Ribeiro, A. M.; Ferreira, V.; Campos, J. B. L. M.; Beleza, VitorinoExperimental particulate fouling studies were carried out for an aqueous suspension of kaolin at a concentration of6 kg/m, flowing at 2.99 x 103 m3/s in a square section horizontal channel and using stainless steel deposition plates. Fouling resistance curves obtained for three positions on the bottom deposition plates showed an initial enhancement of heat transfer, but as the deposition process continued, the fouling resistance increased until it reached a constant value. Measurements of the mass and the thickness of the dry kaolin deposits on the plates at the end of the experiment (144 days) showed that deposition was higher for the bottom plates than for the top ones.
- Incidence of nitrate, nitrite, chloride and phosphate in groundwater in Modivas, PortugalPublication . Silva, Susana; Sousa, José; Ramalhosa, M. J.; Antão, M. Cristina; de Sá Barroso, Maria de Fátima; Pina, Maria de Fátima; Pina, Maria de Fátima; Delerue-Matos, Cristina; Delerue-Matos, Cristina; Beleza, VitorinoThe aim of this project consisted in the evaluation of chemical quality of groundwater in domestic wells situated in the village of Modivas, which belongs to the district of Porto, in north of Portugal. The population doesn’t have a public water supply system and the groundwater is a significant source for domestic, livestock breeding and agricultural use. The quality of water samples were collected from domestic wells with an approximate deph of 15m and the quality has been investigated with respect to pH, conductivity, temperature, nitrate, nitrite, phosphate and chloride. Geographical coordinates were also measured at each location, using a GPS device. The obtained results show that a strong nitrate contamination exists in the studied area. A very small percentage of wells (2%) were above the guideline for nitrite. As for the other parameters (chloride and phosphate) the results never exceeded the legal limit.
- Re-utilization of sewage sludges as a precursor for activated carbon productionPublication . Gutiérrez, Maria S. C.; Rocha, Maria J.; Mendes, Sandra S.; Freitas, Maria Madalena; Silva, Paula; Beleza, VitorinoThe possibility of re-utilization of sewage sludges from wastewater treatment plants as raw-material for activated carbon production was investigated. Activated carbons were prepared from secondary sludges by physical activation with carbon dioxide. Pyrolysis was carried out in nitrogen atmosphere at 873 K during 3 h. Physical activation was performed in pure CO2 flow, for 1h, at temperatures between 1123 and 1223 K. Global yields of the process range from 30 to 4o wt %. Activated carbons have surface areas from 60 to 100 m?/g and micropore volumes up to 0,020 cm3/g. Porous structure presents about 50% microporosity. A chemically activated sample (H.SO,, 973 K, 15 min, N, flow) was also prepared for comparative purposes. Results show that activated carbons produced have potential to be used as pollutant adsorbent, but further optimization studies will be needed in order to improve its porous structure.
- Dimensionamento de juntas de dilatação incorporadas em obras de condutas de abastecimentoPublication . Félix, Carlos; Dias Silva, Hugo Filipe; Silva, J. Gabriel; Figueiras, J.; Beleza, VitorinoAs condutas de abastecimento de água são geralmente enterradas. No entanto em casos específicos, como por exemplo em travessias aéreas, existem troços de conduta que estão ou suspensos ou a superfície do terreno encontrando-se sujeitos as acções resultantes das variações de temperatura. Nestas situações é comum dotar o troço de conduta, normalmente fixo entre duas ancoragens, de juntas de dilatação que absorvam as dilatações e contracções a que estão sujeitos. Contudo, a presença de juntas de dilatação no sistema adutor introduz no sistema conduta/junta de dilatação acções de valor não desprezável. Assim é da maior importância que em fase de projecto as características destas juntas sejam devidamente especificadas, sejam claramente identificadas e quantificadas as acções envolvidas, se dimensionem os apoios/guiamentos da conduta e se avalie a segurança da conduta com base em modelos de analise que tenham em atenção efectivas condições de apoio, em particular a interaçãao conduta/ estrutura de apoio. Nesta comunicação identificam-se os aspectos mais importantes a considerar nas varias fases das obras que incorporem juntas de dilatação telescópicas.