Browsing by Author "Alves, Nuno"
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- Estudo de viabilidade para a reutilização de águas residuais urbanas tratadas na recarga de aquíferos - normativos de qualidadePublication . Alves, Nuno; Stigter, Tibor Yvan; Carvalho, AméliaDuring the Polis Program of the city of Beja an urban park with an area of about five hectares was created, with many garden and leisure areas. Given the limitations of the city in terms of water resources, the Beja Water and Sanitation Utility (EMAS de Beja) decided to improve the existing treatment at the Sado WWTP to allow its use for irrigation of the park. Given the advantages of groundwater storage, the aim of the present work was to study the potential use of reclaimed wastewater from the Sado WWTP for local aquifer recharge and subsequent indirect use for irrigation of the referred park. The characterisation of the local aquifer hydrogeology (Beja Gabbro Aquifer System) led to the conclusion that infiltration basins were the most suitable method of recharge. Based on scientific papers published in this field, as well as national and international standards, a set of quality criteria was defined to be met by the Sado WWTP effluent for artificial recharge using the referred method. Among the quality criteria, emerging contaminants such as endocrine disruptors and parabens were analysed, as well as microorganisms resistant to chemical oxidation, e.g., Giardia lamblia and Cryptosporidium sp..
- Ocean acidification will not affect the shell strength of juveniles of the commercial clam species chamelea gallina: implications of the local alkalinization of seawaterPublication . SORDO, LAURA; Esteves, Eduardo; Valente, Joana F.A.; Duarte, Catarina; Alves, Nuno; Baptista, Teresa; Gaspar, Miguel; Anibal, JaimeOcean acidification (OA) is expected to decrease the strength of bivalves' shells, especially during the early stages of development, with negative consequences to the resilience of natural populations and the economy. The objectives of the present study were to assess the long-term effect of increasing pCO(2) after 217 days of exposure under controlled conditions of pH of similar to 8.2, 8.0, and 7.7 on the strength and integrity of shells of juveniles of the commercial striped venus clam Chamelea gallina. Shell strength was estimated through compression tests and integrity through scanning electron microscopy (SEM) and dispersive X-ray analyses (EDX). The results showed that under increasing pCO(2) the shell strength of juveniles is unaffected, which could be related to the locally elevated total alkalinity of seawater with respect to other parts of the coastal lagoon. However, despite this, it was also observed that the juvenile clams exposed to elevated pCO(2) decreased their shell thickness and increased the porosity of their prismatic layer. Under future OA conditions, these changes could eventually compromise the integrity of the shells, becoming more vulnerable to the attack of predators and breakable during fishing operations. Future studies should address the plasticity of the organisms and the effect of the alkalinization of seawater on the resilience of shellfish juveniles under global change conditions.