Close or not so close? Provenance studies of megalithic monuments from Alentejo (Portugal)

There has been a significant amount of studies about megalithic tombs conducted in the Alentejo region. However the geological provenance of monoliths used in the construction of those tombs usually was not a priority among researchers with rare exceptions (Dehn, Kalb and Vortisch, 1991; Boaventura, 2000). Recent studies of dolmens (Oliveira, 1997 and 2006; Gonçalves, 2003) refer only to a brief characterization of rocks, such as "granite or schist slabs", highlighting certain types if the geological stratum is identical or not to the stone blocks. On the other hand, when the type of raw material appears to be similar with the bedrock, it is common and empirically assumed its local provenance. With the aim of testing and expand the knowledge about the provenance of the slabs used in the construction of megalithic tombs, several lithic samples from dolmen slabs and outcrops in their surroundings were collected for analysis and comparison. The samples were characterized by petrographic studies in thin section as well with a geochemical analyses performed by XRF that gives major elements as well some trace elements. The dolmens tested for this project are located roughly between the northeast to west of the town of Monforte (Upper region of Alentejo, Portugal) and are named, from south to north, as Serrinha, Rabuje group (1 to 5), Geodésico de Besteiros 3 and Velho. The field work and petrographic studies revealed that the slabs are constituted mainly by several types of granitoids (gnaissic, red, white, tonalitic), amphibolites and mottled schist shale. The comparison of chemical analyses between slabs and selected outcrops revealed that the provenances are in most of the cases from the nearby geological stratum. In fact, major elements (e.g. MgO, SiO2, CaO) as well trace elements (e.g. Sr, Y, Zr, Nb) compositions are similar on slab samples and in rocks from the outcrops. If in terms of major elements a similarity was already expectable, or easier to obtain, the trace elements (namely immobile elements such as Y or Nb) compositions corroborated that slabs and geological bedrock were alike. The capstone slab that covers the dolmen of Rabuje 1 group does not belong to the nearby geological stratum. Nevertheless, a probable matching source-outcrop was located sampled and characterized in terms of geochemistry and petrograpphy and compared with the megalithic capstone. This work allowed a better characterization of the rocks used in megalithic tombs as well as corroborat a pragmatic attitude of Neolithic populations in the search of the appropriate slabs for construction as proposed previously (Boaventura, 2000). When available, the megalithic stones were likely collected from the nearby stratum and therefore the distances traveled were small (in situ or less than 1-2 km). Nevertheless, when the type of stone needed was not available in the vicinity (e.g fracturing provided only smaller stones) it would be necessary to travel longer distances, up to 8 km (Boaventura, 2000), as in the case of the dolmen of Rabuje 1. Boaventura, R. (2000) - A geologia das Antas de Rabuje (Monforte, Alentejo), Revista Portuguesa de Arquelogia. Vol. 3;2.pp-15-23. Dehn, W.; Kalb, P.; Vortich, W. (1991) - Geologisch-Petrographische Untersuchungen an Megalithgräbern Portugals. Madrider Mitteilungen, 32, p. 1-28. Oliveira, J. (1997) - Monumentos megalíticos da bacia hidrográfica do Rio Sever. Ibn Maruan. Castelo de Vide. Special Edition. Oliveira, J. (2006) – Património arqueológico da Coudelaria de Alter e as primeiras comunidades agropastoris. [Évora]: Colibri

Modelação do consumo de cloro na oxidação de matéria orgânica presente em águas superficiais com diferentes origens (Portugal e Angola)

A qualidade da água para consumo humano é uma condição indispensável na sociedade atual. Entre os requisitos de qualidade de uma água de referir a isenção de contaminação bacteriológica, o que requer um processo de desinfeção, normalmente por cloragem, como etapa final do processo de tratamento. Na operação de cloragem é consumido cloro por oxidação de compostos orgânicos presentes na água. Neste trabalho, foi estudado o consumo de cloro pela água bruta do Rio Bengo (Angola) e da água à saída da ETA de Lever (Portugal). Em particular, estudou-se a cinética do decaimento do cloro no seio de amostras de água, tendo sido realizados vários ensaios distribuídos por duas séries: 1ª) variou-se a concentração de cloro, mantendo constante o teor de matéria orgânica (expressa como oxidabilidade ao KMnO4), à temperatura de 25ºC e 35ºC, e na 2ª) foi mantida a concentração de cloro e fez-se variar a oxidabilidade. Foram ajustados diferentes modelos cinéticos aos resultados experimentais de decaimento de cloro e de matéria orgânica; o modelo de primeira ordem paralela foi o que descreveu de forma mais satisfatória a cinética de consumo do cloro.info:eu-repo/semantics/publishedVersio

Biosorption of lead from simulated industrial wastewaters by aquatic bryophytes

Aquatic bryophytes are frequently used as biomonitors for trace metals in aquatic ecosystems. Nevertheless, their special characteristics also allow using them as biosorbents to clean industrial wastewaters. As biosorption is a low cost and effective method for treating metal-bearing wastewaters, understanding the kinetics process is relevant for design purposes. In this study, the performance of the aquatic bryophyte Fontinalis antipyretica for removing lead from simulated wastewaters has been evaluated. Three kinetic models (pseudo-first order, pseudo-second order and Elovich) were fitted to the experimental data and compared using a Test-F. Previously, the effect of parameters such as the initial solution pH, contact time and initial metal ion concentration, on biosorption was investigated. The initial pH of the solution was found to have an optimum value is in the range 4.0-6.0. The equilibrium sorption capacity of lead by Fontinalis antipyretica increased with the initial metal concentration. For an initial metal concentration of 10 mg L-1, the uptake capacity of the moss, at equilibrium, is 4.8 mg g-1. Nevertheless, when the initial concentration increases up to 100 mg L-1, the uptake of lead is 10 times higher. The pseudo-second order biosorption kinetics provided the better correlation with the experimental data . The applicability of the Langmuir and Freundlich adsorption isotherms for the present system was tested. The maximum sorption capacity of mosses was 68 mg g-1

Estudo preliminar de tratabilidade do lixiviado do aterro sanitário de Luanda, Angola; processo de Fenton

O lixiviado de um aterro sanitário resulta da percolação de água das chuvas e dos processos de degradação dos resíduos; recolhido pelo sistema de drenagem não deve ser lançado diretamente no meio hídrico por apresentar elevado potencial poluidor. É prioritário o tratamento adequado, reduzindo a carga orgânica, com o objetivo de cumprir os padrões de emissão de efluentes e desta forma garantir a qualidade da saúde pública. Neste estudo foi caracterizado o lixiviado do Aterro Sanitário dos Mulenvos, e realizado um estudo preliminar sobre a eficiência do processo Fenton (POA), na remoção da matéria orgânica (expressa como DQO). Foram avaliadas/selecionadas as condições de operação adequadas para o processo (temperatura, pH, dosagem de H2O2 e razão H2O2:Fe2+).info:eu-repo/semantics/publishedVersio

Modelling of lead removal by an aquatic moss

Aquatic bryophytes are frequently used as biomonitors for trace metals in aquatic ecosystems. Nevertheless, their special characteristics also allow using them as biosorbents to clean industrial wastewaters. As biosorption is a low cost and effective method for treating metal-bearing wastewaters, understanding the process kinetics is relevant for design purposes. In this study, the ability of the aquatic bryophyte Fontinalis antipyretica to remove lead from simulated wastewaters was evaluated. Three kinetic models (pseudo-first order, pseudo-second order and Elovich) were fitted to the experimental data and compared by the F-test. Previously, the effect on biosorption of parameters such as the initial solution pH, contact time and initial metal ion concentration was investigated. The initial pH of the solution was found to have an optimum value is in the range 4.0-6.0. The equilibrium sorption capacity of lead by Fontinalis antipyretica increased with the initial metal concentration. For an initial metal concentration of 10 mg L-1, the uptake capacity at equilibrium was 4.8 mg g-1. Nevertheless, when the initial concentration increased up to 100 mg L-1, the uptake of lead was 10 times higher. The pseudo-second order biosorption kinetic model provided the better correlation with the experimental data (R2=1.00). The applicability of the Langmuir and Freundlich adsorption isotherms to the present system was also assessed. The maximum lead sorption capacity by Fontinalis antipyretica was 68 mg g-1

Briófitas aquáticas como bioindicadores da poluição de águas superficiais por metais pesados

A bacia do Rio Ave tem sido ao longo dos anos alvo de descargas ilegais dos mais variados tipos de indústrias, tendo atingido níveis de contaminação por metais pesados que põem em perigo todo o ecossistema aquático. O homem, como elemento último dum conjunto de cadeias alimentares, por ingestão de peixe, utilização da água para rega ou consumo de água produzida a partir das águas captadas nesta bacia, será certamente o mais afectado com consequências múltiplas para a sua saúde. A relativa abundância de espécies de briófitas aquáticas fez com que fossem aproveitadas como bons indicadores de poluição por metais pesados em vários estudos sobre a qualidade de águas superficiais. A utilização de briófitas aquáticas surgiu, assim, como um instrumento de avaliação global da contaminação por metais pesados (Cd, Cr, Cu, Fe, Hg, Ni, Pb e Zn) na bacia hidrográfica do Rio Ave (Norte de Portugal). Os resultados indicam factores de contaminação máximos nos musgos entre 2,6 / 2,5 (Hg) e 86,0 / 28,8 (Zn) em duas campanhas realizadas em épocas diferentes do ano, respectivamente. Os locais de amostragem foram classificados em três classes de qualidade. Na 1ª campanha, duas das estações (Rio Este) foram classificadas na Classe C (maior poluição) não existindo nenhuma na Classe A. Registou-se uma melhoria global significativa na 2ª campanha

Removal of Cd2+ and Cu2＋ by free and immobilized saccharomyces cerevisiae: kinetic and equilibrium modeling

Removal of Cd2+ and Cu2＋ by free and immobilized Saccharomyces cerevisiae: kinetic and equilibrium modeling

Uptake and release of zinc by aquatic bryophytes (Fontinalis antipyretica L. ex. Hedw.)

The zinc uptake and posterior release by an aquatic bryophyte—Fontinalis antipyretica L. Ex Hedw.—was experimentally studied in laboratory exposing the plants to different zinc concentrations in the range, 1.0–5.0 mg l 1, for a 144 h contamination period, and then exposed to metal-free water for a 120 h decontamination period. The experiments were carried out in perfectly mixed contactors at controlled illumination, using mosses picked out in February 1997, with a background initial zinc concentration of 263mg g 1 (dry wt.). A first-order mass transfer kinetic model was fitted to the experimental data to determine the uptake and release constants, k1 and k2; the zinc concentration in mosses at the end of the uptake period, Cmu; and at the equilibrium, for the contamination and decontamination stages, Cme and Cmr; respectively. A bioconcentration factor, BCF ¼ k1=k2 (zinc concentration in the plant, dry wt./zinc concentration in the water) was determined. A biological elimination factor defined as BEF ¼ 1 Cmr=Cmu was also calculated. BCF decreases from about 4500 to 2950 as Zn concentration in water increases from 1.05 to 3.80mg l 1. BEF is approximately constant and equal to 0.80. Comparing Zn and Cu accumulation by Fontinalis antipyretica, it was concluded that the uptake rate for Zn (145 h 1) is much lower than for Cu (628 h 1) and the amount retained by the plant decreased by a factor of about seven