The ITRAX core scanner, a useful tool to distinguish anthropic vs. climatic influences in lagoon of Aveiro (N Portugal)

The main goal of this work is to distinguish anthropic and climatic influences in sediments from the lagoon of Aveiro (Portugal). This study is based on a core (240-cm long) collected in Murtosa Channel. Optical and X-radiographic images and high-resolution elemental profiles were acquired with ITRAX micro-X-ray fluorescence (XRF) core scanner. Samples collected at each ≈3 cm along the core were analysed for grain size and total organic carbon. Furthermore, the fine fraction of selected layers was subjected to geochemical analysis by ICP-MS, after total acid digestion of the sediments, and mineralogical analysis, by XRD techniques. A radiocarbon age was determined by AMS, using molluscs shells collected at a depth of 90 cm. Sediments along the core are composed by fine and medium sand, with several mud layers. Sediments composing the first 100-cm may have been deposited after 1950, as it is indicated by the radiocarbon data, the increasing trend of Zn/Al, Pb/Al and Cu/Al and total concentrations of Zn, Pb, Cu, V, Cr, As and Ni in this interval that therefore might be linked with industrial activities of Chemical Complex of Estarreja. The progressive increase of Si/Al, Cl/Al, Rb/Al, K/Al and Br/Al and reduced Al concentrations, from the base to the top of this core, are interpreted as being related to higher marine influence and greater differences in tidal currents with longer exposition to air of the sediments with the consequent formation of brines favouring minerals precipitation in the area (e.g. anhydrite). These results seem to be a consequence of several works developed over time like: i) dredging to improve the navigation access to the harbour, located in the external sector of the lagoon; ii) the control of the course of some rivers influencing the supply of sediments. The tendency of sea level rise may have also emphasized the gradual increase of marine influence in this area. Fine-grained sections, related to an increase in Al, phyllosilicates, organic matter, pyrite and siderite contents would be attributed to phases of greater supply of fine-sediments during heavy rainfall events by the nearby Antuã river and other streams during negative phases of North Atlantic Oscillation. Higher deposition of organic matter enhanced diagenetic changes with pyrite and siderite formation. In the bottom of the core another record of pollution was unveiled to mining activities at the beginning of 20th century.FCT de Portugal - C/CTE/UI4035/2011CNPq - 401803/2010-

Atmospheric dust deposition and levels of trace elements in an industrial city in the Portuguese coastline

O presente estudo pretendeu (i) identificar padrões geoquímicos espaciais e temporais na deposição atmosférica, e (ii) avaliar potenciais contribuições de fontes locais e alóctones para a composição química das poeiras atmosféricas no concelho de Estarreja. Dois coletores foram colocados em áreas exteriores de duas escolas localizadas poucos quilómetros a sul da zona industrial. A recolha das amostras foi realizada mensalmente, de maio a agosto de 2018. As frações solúvel e insolúvel da deposição atmosférica foram analisadas por ICP-MS para determinar as concentrações quase-totais dos elementos químicos. Os resultados mostram a ocorrência de dois eventos distintos de maior fluxo de deposição atmosférica: (i) um em maio, caracterizado pela deposição de elementos traço em formas solúveis, detetado em ambas as escolas e (ii) um segundo em agosto, caracterizado pela deposição de elementos maiores em formas insolúveis, detetado apenas na escola mais distante do complexo industrial. No geral, os resultados indicam uma deposição antrópica de aerossóis em maio e uma deposição de partículas litogénicas em agosto.Due to their high toxicity and reactivity in atmospheric particles, metl(loid)s are a category of pollutants of great concern in air pollution. The present study aimed (i) to identify spatial and temporal geochemical patterns in atmospheric deposition, and (ii) to evaluate potential contributions from local and regional sources to the chemical composition of atmospheric dust, in the industrial city of Estarreja. Two collectors were placed in exterior areas of two schools located few kilometres south from the industrial zone, one within an urban setting and another in a rural environment. Samples were collected monthly from May and August 2018. The soluble and insoluble fractions of atmospheric were analysed by ICP-MS to determine near-total concentrations of the chemical elements. The results indicate two distinct events of higher atmospheric deposition flux. The first event, detected in both schools, occurred in May and is characterized by the deposition of trace elements in soluble forms. The second occurred in August and is characterized by the deposition of major elements in insoluble forms. This later episode was detected only at the school furthest from the industrial complex. Overall, the results indicate an anthropogenic aerosol deposition in May and a lithogenic particle deposition in August.Este trabalho é cofinanciado pela União Europeia através do Fundo Europeu de Desenvolvimento Regional, baseado no COMPETE 2020 (Programa Operacional de Competitividade e Internacionalização), no projeto ICT (UIDB/04683/2020), no projeto GeoBioTec (UIDB/04035/2020) e nos fundos nacionais fornecidos pela Fundação para a Ciência e Tecnologia. Os autores agradecem à Direção, aos docentes e aos funcionários do Agrupamento de Escolas de Estarreja a preciosa colaboração durante o período de recolha das amostra

Factors controlling the recent sedimentation in the upper continental slope of the Jacuípe Basin (NE Brazil)

This work is based on textural, mineralogical (XRD) and compositional data of 50 bottom sediments' samples in the upper continental slope between 80-1000 m water depth of the Jacuipe Basin, northern region of Bahia State (Brazil). It intends to study the recent sedimentary coverture and infer possible conditioning factors influencing the recent sedimentation in this region. Despite the study area has been considered oligotrophic, pyrite that is supposed to be mostly the result of the initial diagenetic processes of organic matter degradation, occurs throughout the upper slope of the Jacuipe Basin. The organic matter flux is abundant enough to establish anoxic environments or microenvironments favorable to the formation and preservation of pyrite. The textural, mineralogical and compositional data allow us to define latitudinal and longitudinal variations of bottom sediments possibly influenced by changes in the geomorphology of the study area and hydrodynamic conditions. The supply of detrital sediments to the southern region seems to be scarce but relatively more abundant in the northern part, closer to the Sao Francisco River delta. The northern region is also more favorable to sediment deposition than the southern one, where erosional processes appear to be more common. This difference may also be ascribed to the process of formation of the Brazil Current, and its southward development. A significant compositional change of sediments was observed at about 435 m depth possibly due to the enhanced influence of the North Brazil Undercurrent

Deposição atmosférica de poeiras e níveis de elementos traço numa cidade industrial no litoral centro de Portugal

International audienceO presente estudo pretendeu (i) identificar padrões geoquímicos espaciais e temporais na deposição atmosférica, e (ii) avaliar potenciais contribuições de fontes locais e alóctones para a composição química das poeiras atmosféricas no concelho de Estarreja. Dois coletores foram colocados em áreas exteriores de duas escolas localizadas poucos quilómetros a sul da zona industrial. A recolha das amostras foi realizada mensalmente, de maio a agosto de 2018. As frações solúvel e insolúvel da deposição atmosférica foram analisadas por ICP-MS para determinar as concentrações quase-totais dos elementos químicos. Os resultados mostram a ocorrência de dois eventos distintos de maior fluxo de deposição atmosférica: (i) um em maio, caracterizado pela deposição de elementos traço em formas solúveis, detetado em ambas as escolas e (ii) um segundo em agosto, caracterizado pela deposição de elementos maiores em formas insolúveis, detetado apenas na escola mais distante do complexo industrial. No geral, os resultados indicam uma deposição antrópica de aerossóis em maio e uma deposição de partículas litogénicas em agosto

Preliminary results of an inter-laboratory study on quantitative phase analysis

Trabajo presentado en el Euroclay, celebrado en Edimburgo (Escocia), del 5 al 10 de julio de 2015Quantitative phase analysis (QPA) of clayey materials using X-Ray diffraction data has always been a challenge. While quantitative methods based on Rietveld analysis offer excellent results for non-clay minerals, they become problematic when high crystallochemical and order degree variations are present in the phases, as is the case of most clay minerals. In the summer of 2014, the Spanish Clay Society (Sociedad Española de Arcillas, SEA) proposed a collective QPA experiment to its members. The aim was to compare the results obtained in different clay laboratories studying the same samples by X-Ray diffraction. This comparative study is a starting point for a long-term work focused on the development of an optimized QPA guide for clay minerals adapted to modern equipment and software. The results presented in this talk are those from the 2014 preliminary study in which the 22 participant laboratories analyzed three samples following their own laboratory routines. The only condition was not to use other complementary techniques for the quantification (e.g. IR spectroscopy, thermal or chemical analysis). The samples were mixtures of nearly pure quartz, feldspar, calcite, alunite, and different clays. Clay minerals included two different smectites (with low and high crystallinity), sepiolite, kaolinite and palygorskite. The set of procedures, technical characteristics of the equipment, and software used in each laboratory was very different and, as a consequence, comparison of the results is not straightforward. The results were classified into "Reflecting Powers Method" (RPM) and “Relative Intensity Ratio (RIR) – Rietveld methods” groups. As it is well known RPM is based on the peaks areas while RIR is based on the peak intensities. As expected, a high dispersion of the results was found both globally and per group. At first glance, RPM returned, on average, better approximations to the true composition of the samples. Interestingly that trend was clearer in samples with clay minerals having higher variability in crystallochemistry and crystalline range order.Peer reviewe

POSSIBLE FUNCTIONS OF BIOMINERALIZATION OF SOME TEXTULARIID (FORAMINIFERA) SPECIES OF THE NW IBERIAN MARGIN

The main goal of this work is to analyze the elemental composition of the test's wall of some species/specimens of Textulariids (sub-class Subclass Textulariia), collected in surface sediments of the NW Iberian Margin. The elemental analysis was based on the Energy Dispersive Spectroscopy (EDS) on the Scanning Electron Microscope (SEM; Hitachi, S4100) of Textularia deltoidea, Textularia agglutinans, Sahulia conica, Karrerotextularia flintii, Siphotextularia heterostoma, Karreriella bradyi, Spiroplectammina sagittula and Arenoparrella mexicana. The elemental concentrations of the species wall were compared with the mineralogical composition (X-Ray diffraction) of the sediments of the stations where these specimens were collected. The results evidence that whereas the test's wall of T. deltoidea, T. agglutinans, K. flintii and S. heterostoma is characterized by the highest concentrations of Ca, Mg and Y and lowest Si and Al contents; S. conica, S. sagittula and K. bradyi present intermediate concentrations of the referred variables but display the highest K content; A. mexicana contains the highest Si and Al contents and lowest Ca, Mg and Y concentrations. Some species that live in siliciclastic sediments contain high calcium content in their tests (such as T. deltoidea and T. agglutinans), whereas some species much common in the deep-sea display high concentrations of lithogenic elements. Results of this work suggest that some Textulariid species can use the test for "storage" and "excretion" of toxic or useless elements that can be used when necessary. These features seem to be functions of biomineralization of the analyzed species and not only the intention of building a protective envelope