Percorrer por autor "Drago, Teresa"
A mostrar 1 - 10 de 19
Resultados por página
Opções de ordenação
- A ciência-cidadã ao serviço da mudança: o exemplo do projeto A Minha PraiaPublication . Gouveia, Licínia; Lourenço, Carla R.; Afonso, João; Freitas, Ricardo; Veiga-Pires, C.; Reis, Emanuel; Rodrigues, Miguel; Gomes, Tiago; Rodrigues, Luís; Mira, Sara; Ferreira, Hélder; Pinto, Andreia; Vaz, Paula; Drago, Teresa; Soares, Isabel; Ramos, AnaVencedor da 1ª edição do Orçamento Participativo Portugal (2017), A Minha Praia é um projeto de monitorização ambiental que pretende sensibilizar para a conservação do meio marinho e estimular hábitos de consumo responsáveis, através de ações de ciência cidadã e civismo ambiental.
- A ciência-cidadã ao serviço da mudança: o exemplo do projeto A Minha PraiaPublication . Gouveia, Licínia; Lourenço, Carla; Afonso, João; Freitas, Ricardo; Veiga-Pires, C.; Reis, Emanuel; Rodrigues, Miguel; Gomes, Tiago; Rodrigues, Luís; Mira, Sara; Ferreira, Hélder; Pinto, Andreia; Vaz, Paula; Drago, Teresa; Soares, Isabel; Ramos, AnaVencedor da 1ª edição do Orçamento Participativo Portugal (2017), A Minha Praia é um projeto de monitorização ambiental que pretende sensibilizar para a conservação do meio marinho e estimular hábitos de consumo responsáveis, através de ações de ciência cidadã e civismo ambiental.
- Challenges in assessing longshore transport along the gulf of cadiz coast: insights from analysis of different wave data sourcesPublication . Santos, Jacqueline; Costas, Susana; Taborda, Rui; Garzon, Juan L.; Drago, TeresaEstimating coastal sediment budgets presents significant challenges due to the complex nature of coastline configurations and the often-bimodal wave regime. This study investigates longshore sediment transport (LST) along the Gulf of Cadiz by analyzing estimates obtained from various wave data sources and employing various approaches. The sensitivity of transport calculations to different wave data sources and approaches is evaluated, and the impact of easterly waves, or “Levante,” is examined for the different approaches. The nearshore wave regime was simulated using the SWAN model, with offshore conditions from ERA5 hindcast and the Faro buoy. Results were validated using observational data and LST was estimated using a deep water approximation of the CERC formula, extracting the net transport and the two components of the sediment transport: west-east and east-west. The results emphasize the critical importance of selecting appropriate forcing for applied models to simulate the nearshore wave regime and estimate sediment transport.
- Environmental change in SW Portugal during the last 3900 years BP: an ostracoda assessmentPublication . Fernandes Martins, Maria João; Cabral, Maria Cristina; Magalhães, Vitor Hugo; Drago, Teresa; Fatela, Francisco; Oliveira, AnabelaOstracod, geochemical, mineralogical, and sedimentological proxies from a sediment core collected off Sagres (southwestern Portugal) were used to reconstruct Holocene environmental and hydrodynamic changes. Reduced variability of geochemical elements between ~4000 and ~1290 calibrated years before present suggests relatively stable conditions, regularly disturbed by higher-energy events. At ~1290 cal yrs BP, a transition from arid to wetter conditions is suggested based on enhanced terrestrial/detrital input after this time. Ostracod assemblages further captured fine-scale hydrodynamic variability, offering greater sensitivity to oceanographic changes. Our results support a broader pattern of middle-to-late Holocene drying conditions in southern Iberia, followed by a shift to wetter conditions during periods of negative North Atlantic Oscillation (NAO) index. Our study provides new data on offshore ostracods from the western Algarve, underscoring their value for high-resolution paleoenvironmental reconstructions.
- Exploring offshore sediment evidence of the 1755 CE Tsunami (Faro, Portugal): implications for the study of outer shelf Tsunami depositsPublication . Kümmerer, Vincent; Drago, Teresa; C. Veiga-Pires, C.; Silva, Pedro F.; Magalhães, Vitor; Mena, Anxo; Lopes, Ana; Rodrigues, Ana Isabel; Schmidt, Sabine; Terrinha, Pedro; Baptista, Maria AnaOuter shelf sedimentary records are promising for determining the recurrence intervals of tsunamis. However, compared to onshore deposits, offshore deposits are more difficult to access, and so far, studies of outer shelf tsunami deposits are scarce. Here, an example of studying these deposits is presented to infer implications for tsunami-related signatures in similar environments and potentially contribute to pre-historic tsunami event detections. A multidisciplinary approach was performed to detect the sedimentary imprints left by the 1755 CE tsunami in two cores, located in the southern Portuguese continental shelf at water depths of 58 and 91 m. Age models based on 14C and 210Pbxs allowed a probable correspondence with the 1755 CE tsunami event. A multi-proxy approach, including sand composition, grain-size, inorganic geochemistry, magnetic susceptibility, and microtextural features on quartz grain surfaces, yielded evidence for a tsunami depositional signature, although only a subtle terrestrial signal is present. A low contribution of terrestrial material to outer shelf tsunami deposits calls for methodologies that reveal sedimentary structures linked to tsunami event hydrodynamics. Finally, a change in general sedimentation after the tsunami event might have influenced the signature of the 1755 CE tsunami in the outer shelf environment.
- Footprint of roman and modern mining activities in a sediment core from the southwestern Iberian Atlantic shelfPublication . Mil-Homens, Mário; Vale, Carlos; Naughton, Filipa; Brito, Pedro; Drago, Teresa; Anes, Bárbara; Raimundo, Joana; Schmidt, Sabine; Caetano, MiguelA 5-m long sediment core (VC2B), retrieved in the Southwestem Iberian Atlantic shelf, at 96 m water depth, was used to assess major changes in climate and human activities during the last 9.7 kyrs. Analytical measurements included sedimentological (mean grain size, and the contents of sand, silt and day), geochemical (major, minor, trace and rare earth elements; REEs) and chronological (Pb-210 and C-14) parameters. Two episodes of increment of fine-grained particles, occurring at 3050 BCE and 1350 CE, suggest the retreat of the coast line to the present level and the beginning of a wetter phase associated with the "Little Ice Age". The North American Shale Composite (NASC)-normalized REE-pattern detected in the shelf is similar to that found in the Guadiana estuarine sediments. The possibility of this estuary as a contributor to the sediment load deposited in the adjacent coastal zone was indicated. Trace elements were significantly correlated with Al until 1850 CE, pointing that grain-size rules its distribution in sediments. The depth variation of As, Cu and Pb enrichment factors relative to background values shows two periods of intense human activity that can be mainly linked to mining: (i) across the Roman Period, marked by low enrichments; and (ii) starting on the second half of the 19th century until nowadays with significantly increased enrichments, especially of Pb and Cu. In addition to As, Cu and Pb, this period is also marked by high enrichments of Hg and Zn. Despite the decrease/closure of sulphide massive deposits mining exploitation (e.g., Sao Domingos, Las Herrerias) during the second half of the 20th century, results showed ongoing input of Pb,Cu, As, Hg and Zn to coastal sediments. Thus, the legacy of contamination by these elements, mainly from leaching of slags and tailings, and remobilization/reworking of contaminated estuarine sediments, is still recorded in marine sediments. (C) 2016 Elsevier B.V. All rights reserved.
- Insights of Pb isotopic signature into the historical evolution and sources of Pb contamination in a sediment core of the southwestern Iberian Atlantic shelfPublication . Mil-Homens, Mario; Vale, Carlos; Brito, Pedro; Naughton, Filipa; Drago, Teresa; Raimundo, Joana; Anes, Barbara; Schmidt, Sabine; Caetano, MiguelStable Pb isotopic ratios and concentrations of Al, Cu and Pb were measured in a 5 m long sediment core (VC2B) retrieved at 96 m water depth in the southwestern Iberian Atlantic shelf. Five phases during the last 9.5 kyrs were identified, two of them (Roman Period and modern mining) marked by a decrease of Pb-206/Pb-207 ratios reflecting additional inputs of Pb derived from mining activities. The Roman Period was also characterized by high Pb-208/Pb-206 ratios suggesting the exploitation of the outcropping portion of the orebody intensely weathered when compared with the other formations later mined. The shift of Pb-208/Pb-206 ratios towards linearity took approximately 1.0 kyrs, which may mirror the time of environmental recovery from the impact of Roman mining activities. The application of a mixing model allowed the quantification of the contribution associated with anthropogenic mining activities to the shelf sediments. The maximum values of Pb contamination occurred in the 20th century. This study gives direct evidence of Pb and Cu exploitation over the last 2000 years. The stable Pb isotopic signatures point to legacy of mining activities that are still the prevailing metal source recorded in the southwestern Iberian Atlantic shelf sediments. (C) 2017 Elsevier B.V. All rights reserved.
- A millennium-scale iberian margin chronology validates the 1755 Lisbon tsunami record and reveals faro recordPublication . Abrantes, Fatima; Domingues Gomes, Sandra; Salvado, Marta; Magalhães, Vitor; Salgueiro, Emilia; Drago, Teresa; Cordeiro, Lívia; Naughton, FilipaThis work presents new data and several age–depth reconstructions based on distinct approaches to improve previously published age models for sedimentary sequences collected on the Iberian Margin middle shelf: PO287 6-1B, 2G (Porto); PO287 26-1B, 3G, and D13902 (Lisbon); and POPEI VC2B (Algarve). The new age models are constructed using radiocarbon dates calibrated with the IntCal20 calibration curve and smooth-spline regressions from the CLAM (non-Bayesian) and Bacon (Bayesian) models. A comparison of the age–depth models generated by the different approaches shows that, beyond the distinct solutions produced by CLAM and Bacon for each site, the differences between the two methods are inconsistent across sites. Furthermore, neither model yielded reliable results for the discontinuous sedimentary sequence with reworked older sediments and a hiatus. In this specific case, the “classical” linear regression (best-fit) approach appears to yield the results that enable intercomparison across all sequences. This exercise confirms the record of the 1755 earthquake and tsunami in the Lisbon core splice and a potential record of the same event in the Eastern Algarve, although the collected data indicate a more distal or lower-energy wave deposit.
- Multiproxy characterization of high energy layers in the nner continental shelf of Quarteira (Southern Portugal) - Preliminary resultsPublication . Santos, Jacqueline; Drago, Teresa; Moura, Delminda; Magalhães, Vitor; Roque, Cristina; Silva, Pedro F.; Rodrigues, Ana Isabel; Terrinha, Pedro; Anxo, Mena; Francés, Guillermo; Lopes, Ana; Alberto, Ana; Baptista, Maria AnaThe occurrence of sedimentary layers indicating high energy events is common in the continental shelves sedimentary record. Their presence has been usually related either to tsunami waves or storm waves. In both cases, the identification of the transport mechanism requires a variety of proxies. This work presents the preliminary results of the analysis of a gravity core (MW-107) collected at ca. 57 m water depth in the inner continental shelf of Quarteira (Algarve) and aims to identify potential high energy events.
- Neoichnology and sediment distribution in tidal flats of the mud‐dominated mesotidal mira river estuary (Portugal)Publication . Shchepetkina, Alina; Drago, Teresa; Santos, Jacqueline; Alberto, Ana; Fatela, Francisco; Freitas, Maria da ConceiçãoInvertebrate burrow morphologies and distributions are presented for the tidal flats of the middle and lower reaches of the tide-influenced (mesotidal), mud-dominated Mira River estuary (SW Portugal) as an analogue for interpreting the ichnology of palaeoestuarine successions. Burrow distributions are revealed using field observations of biogenic and physical sedimentary structures, trace makers, collected grab samples, push cores and lab measurements of grain size, organic matter and calcium carbonate content and linked to physico-chemical stresses. Estuarine tidal-flat surface open burrow distribution and bioturbation intensity are analysed in plan view using free scientific image analysis software (ImageJ) to obtain burrow density, total burrow area and minimum and maximum burrow diameters. The total tidal flat area occupied by organisms ranges from 0.8% to 4.1% in the middle estuary and is 1.4% in the lower estuary. These equate to a bioturbation index of one to two (BI 1–2). However, computed tomography (CT) of push cores (cross-sectional view) taken on the same tidal flats shows sparse to complete bioturbation intensity (BI 1–6), revealing that tidal flat sediments tend to be more biogenically reworked cumulatively over time with overprinting of subsequent tiers and/or recolonized. CT scanning also allows the identification of more burrow types, demonstrates infaunal tiering and provides insights into trace-fossil preservation potential. This research shows that the trace communities are heterogeneous and change spatially and temporally along the Mira River estuary, reflecting a physico-chemical gradient and seasonality. This trend signals changes in sediment composition, substrate type and consistency (sediment compaction and subaerial exposure), salinity, oxygenation, temperature, pH and interplay of tidal versus hydraulic energy.